Interesting info on Boomtubes

Interesting info on Boomtubes:
I have heard this axleback on several you tube vids and they are awesome on a stock vehicle!!!! The price can't be beat at $289-299 a set, but nobody knew who made them. I did some intensive e-mailing and it turns out that Mac does make them but they do not advertise them on their site. The reason they gave was that they make them for a private retailer and do not own the patent. They also provided a phone number which I have not yet called. Several companies sell these, but beware of the e-bay listings because I have already spotted one fake.
These things are very aggressive but have little to no drone in the car, judging by a video I saw. The only downside is that some of the welds are kinda crappy looking and some people have had issues with scratches/marring of the pipes. None of what I have seen would be noticeable from looking at the back of the car and the issues could be due to shipping.
So, anyone have these? Opinions? As soon as my taxes get here, I'm going to pull the trigger as these are the best sounding, least droning, least expensive axlebacks I have ever heard on the S197.

From listening to sound clips, they sound very good with the stock H-pipe. I would assume the would also sound good with a prochamber. That being said, lastcallracing has them on special for $274.99. I know both the owners. Really good guys. Here is a link. http://www.lastcallracing.com/pac-bt2005.html

I noticed the suspect welds also, but, have had zero issues with them. I had a friend do a drive-by so that I could hear the car from a different perspective. Sounds good.

Thanks Grant!

They're actually made by Pacifica Performance, who I believe is something like MAC's sister company. We put some of these on a customer's car the other weekend, and I kinda wish they had something like these for my beloved SN-95s. They slip on so easily, and the design is rather nice, with no muffler, but with a whole bunch of baffling in the tips. This went on a mostly stock GT, and sounded absolutely fantastic. I can't recommend them enough to the S197 guys, as they're close to the sound the SN-95/Fox guys would get after doing a much more expensive catback and midpipe combo.

And yeah, we've got a great price on them since our buddies up the street make them. Gotta love Southern California

I just put on the boomtubes, or boom tubes. The rest of my exhaust is stock. I have been watching you tube videos of S197s exhaust for about 6 months, and I think the boom tubes are closest to the sound I want. Very similar to the original Bullitt.

On the outside, they sounds absolutely amazing. With the windows down, they sound amazing. With the windows up, there is some drone.

I have been experimenting with sound baffles in the trunk, and I seem to able to reduce the drone, or change the rpm that it comes in at. Also, this is my first aftermarket exhaust install, so I cant say if the drone is a lot or very little compared to other aftermarket systems. It is strange, I was so excited to get them on the car, and now that they are on, I just want to be outside the car when I am driving. Not because of the drone, but because they just sound so amazing on the outside. I suppose this wont be an issue once the weather warms up.

Also, been doing a lot of research on drone and I think it is possible for some people to experience bad drone, and others not, in the same car. The cab of the car is essentially acting as a resonant cavity, and so there will be nodes within the car that have no drone whatsoever, no matter what the system.. unless the drone is resonating at the first fundamental freq of the cab.

Anyhow, my wife was in the car and she did not notice any drone. I may just be being picky. Then again, as I write this, I am popping my ears to recover from the beating they just took as I drove around testing the system. I wish this were more of a slam dunk like the other mods I have done to the car, but I think I will have to find some way to reduce the drone or else get rid of them. If anyone has any ideas, please let me know.

Well, as far as drone goes: in the past when the mufflers were in the traditional position, I have always solved it by shortening the length of one pipe after the convertor moving one muffler closer or farther away. Ford did this on stock Mustangs in the mid 80's to solve the problem. I guess it would still work, but you might notice it on these cars since the mufflers or boom tubes are at the back of the car.
If you do decide to sell, pm me as I'm interested.

Thanks for the info, I am still researching the drone issue. I think what I am experiencing may NOT be traditional exhaust drone. It is a sort of cabin resonance, but it is very slight. It is not a noise to itself, it is just a slight inaudible throb. I have read some posts on other forums about drone from other axlebacks and apparently drone can be very intense. I definitely could not describe this as intense. Most mustang owners seem to experience drone at 2k rpms, and this begins at 2k very slightly, but peaks at 2800.

Anyhow, I drove around today with the windows down even though it was 40 degrees. I love the sound of these boom tubes. It is just an amazing, perfect snorting aggressive sound. But they are not loud at all, I can pull into my home garage at 2am without annoying any neighbors by keeping it under 1500 rpm.

I think I am going to revise my previous statement. I am definitely going to keep the boom tubes. I will try and solve the slight resonance, but if I cant, so be it. I can avoid 2800 rpm in the winter, and keep the windows down all summer.

I can't wait to install them on my car (tax return). I've listened to countless sound clips of nearly all axelback systems out there and NOBODY has anything negative to say about them (minus the rare welds). I was/am concerned about cost and debated the PYPES muffler deletes. They sound cool, but some clips have some popcorn pop noises during low to medium revs. Why don't the boom tubes do that? Are the preforations (Spelling?) really that good at negating that; is there a packing material inside that can degrade over time? Last question. Where in Socal do they make them and can I pick them up in person (live in So Cal)?

I know the price is good and will get the boom tubes. Just wondering if it is fiberglass that acts as the packing material and if over time the fiberglass will rattle around in the tips walls.

You could e-mail Mac and ask them if there is packing material.
Grey Diesel: could your problem be with other things resonating in the interior such as the e-brake handle or is it definitely exhaust causing the problem? If you plan on changing your rear end gearing, that would move the exhaust tones to where you wouldn't be bothered. Then, there is always dynamat or less expensive alternatives to sound deadening.

I think I have the resonating problem figured out. I took out all the trunk carpet and spare tire today, drove around a bit, and noticed a huge increase in drone. That leads me to believe that, as you suggest, if I add some dynamat to the trunk, the problem will be solved. I have been doing some research on dynamat, and it sounds like its a good/fun mod anyway.. heading to the local retailer today and I'll probably have it in the trunk soon.

I'll post the results.

TheVat - I dont think there is any packing material in these things. You can see inside them pretty well, and I dont see anything. Brenspeed has a pic of the inside of the boom tube. It looks like it is just a secondary interior steel tube with baffling. Mustang GT Boom Tube Stainless Axleback (05-08)

Thanks. Looking forward to the results.

I wish I had a picture for you, but from when I saw it, there appeared to be nothing fiberglass, but instead, just a bunch of ... uh, aerodynamic metallic cheese graters I haven't yet heard any issues from our customers of these breaking down or the sound changing over time, as it really is a magnificent product.

-Patrick

i have had the boomtubes since 07 there is no packing material. heres what the inside looks like.


i recently took them off, and welded in some M80's and MBRP muffler deletes out back. i just put the old boomtubes on my dad's mustang, and there is rattling from the baffles coming loose. so if you look at the welds on the baffling, they arent that great and in time they will come loose. when i got them back in 2007 they were $200, i guess you get what you pay for.

at first i couldnt figure out what the rattle was. i tried shaking the exhaust, nothing. checked all the clamps, they were all tight as could be. checked clearance and it wasn't an issue. then i hit the boomtubes with my hand, and there was the rattle. i would here it when driving my dads car when i go over a bump and stepping on the throttle at the same time. the boomtubes do sound great, but the quality is not that good.

Update on the drone issue. I installed some dynamat extreme today. (I would have gone with Second Skin Damplifier, as it seems to be a better product for less money, but none of my local dealers had it in stock. Plus, I was able to talk the dynamat guy into giving it to me for near the price of the Damplifier)

So, I put the dynamat in stradigic places in the trunk (large areas of blank steel), drive around, and there was very little change in the drone. I then go ahead and fill nearly the entire trunk up with dynamat, drive around, and there was a very small decrease in the drone. BUT, while installing the dynamat, I would tap on an area and see how it would resonate. In doing this, I found an area in the spare tire well that you can easily vibrate the entire car with a simple rap of the knuckles. (see attached pics, the first shows the free steel drum you get with every purchase, and the second shows where you can knock and get major vibrations throughout the car. You can see, it is even vibrating the camera ) I think this is where the drone is coming from. That spare tire well is sort of ridiculous, it is literally a steel drum right next to the exhaust pipes. Even covered in dynamat extreme, it was able to resonate when I tapped on it.

I then bought some hardware so that I could buckle the tire into the well very tightly, hoping that the spare tire would be able to dampen the resonance if it is attached tightly enough. This may have helped some, but did not solve the problem completely.

I then took out the back seat and dynamatted that, no change in drone.

Finally, with my very last bit of dynamat, I took up the carpet in front foot wells and put in some dynamat there. That worked! The drone is nearly completely gone. I can still tell there is extra resonance at the same rpm level as before, but only because I know where to listen.

Long story short, dynamat in the front foot wells does the trick with boom tubes. If you have drone with boom tubes, or are thinking of buying boom tubes, figure in another $50 for 10 square feet or so of dynamat in the front foot wells. Now, the car sounds absolutely amazing, at all rpms.

Oh and, my stereo sounds way better. The dynamat did live up to the hype in that department.

Bought and installed the boomtubes yesterday. Patrick and Emmerson at LastCallRacing are good guys/very helpful and accomodating with placing the item at will call at PacificPerformance. I met with Dan, the designer of the kit. He offers a lifetime warranty on the boomtubes and will replace them no problem if something fails, although he doubt's it will. I told him about the possible broken baffles and he assured me that it is the only one he's heard break in nearly 1000 that he has built. He's a very good guy and would buy from him in the future. Anyway, the boomtubes are without words the most amazing sounding exhaust I have heard on a S197. This is kinda difficult to explain, but all of the other kits I have heard seem to produce a "manufactured" sound from the exhaust that differs from the engine up front. With the stock mufflers this is evident. The boomtubes although a straight pipe with louvers produce a sound that seem to be a huge multiplication in the engine sound. You can hear every fire, cams, intake. The tone is very crisp/clear and is not raspy like a traditional straight would be, but just as loud. Almost sounds like a 4V, Power difference, I can't really tell but it does rev up a bit quicker. Yes, you will hear drone. It's not bad at all during the daytime, but at night it's a lot louder and drones a bit more (Colder air?). Thanks to the hard work by GrayDeisel, I probably will dynomat the front footwells because I drive a lot at night. Had to have a muffler shop raise the right tip up slightly and the supplied C clamps didn't hold the overaxel pipe with the connecting pipe at all. The shop just spot welded the two parts together and it's in place now. Dan at pacificaperfomance is sending me new clamps but has no warranty issues as long as no shop modify's the louvers inside the HUGE tip. A lot of cars on the road drove right next to me with thumbs up wanting some rev's. Coudn't be happier, and the wife thinks they sound good too, which is always good!

I'm amazed that the c-clamps didn't work for you. I've had nothing but great success installing those kits, doing most in about 20-25 minutes with the most time consuming part spent taking off the stock setup. But yeah, the sound is hard to describe, and not in a bad way.

Glad to hear that you're liking it, and I'm sorry that I misquoted you on the travel time. If you made it in an hour, you must have been moving Should you feel like willcall'ing from us again, I'll get the exact distance for you instead of guessing

-Patrick

Hey TheVat, thanks for posting. I am glad to hear you got something from my post. I hope that dynamating the footwells works for you, and would be curious to hear about your experience. If you can find some Second Skin Damplifier, I understand that is just as good if not better than dynamat, and about half the cost. Also, I am thinking about putting some spray sound deadener on the underside of the footwells, just to beat a dead horse. I like your thinking about the air temp, as it has been pretty cold recently. Also, I do have a CL racer intake, which did change the exhaust tone of the stock muffs quite a bit, so I am guessing that could lead to increased drone with the boomtubes (or any axleback).

Sometimes, I hear what comes out the back of my car and I think, holy crap, is that coming from my little ol 4.6 litre. The web videos of these things really dont show how deep the engine sounds at low rpms, then when you hit it... just amazing. I love these things.

oh and, the c-clamps did work just fine for me. I had to tighten them a bunch more than I thought they would tighten, but overall the install was a breeze.