Sound level with 3" tails vs. 2.5"??
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I don't know for sure but I think the off-road X is doing more for your sound than the tailpipes themselves. However if you end up dropping the 3" tailpipes I would be interested in them if they have the ball/socket joint to fit into my 2.5" MAC flow tubes 
Just checked and the tips are actually 3.5". Is it safe to assume that the rear section of the MAC tails is not interchangable between the 2.5 and 3" pipes? Meaning, I wont be able to just unbolt the rear 3" section and bolt up the 2.5" rear stainless section. The over axle pipe coming out of the muffler is 3" and is welded to the muffler.
I think they may be interchangeable, only because of the socket collector they use (like headers). The pipes don't gain their size until after that portion of the tailpipe. It's won't be like trying to mate a 2.5" straight pipe to a 3" straight pipe where you'd need a reducer of sorts.
bentley429isBAC
10 Year Member
1991notchbackLX
Active Member
3" tails will be louder than 2-1/2" tails. You're opening it up, so it's gonna echo out. Hack Job had stock manifolds, BBK H-pipe, MAC tru-fit bolt together cat-back. Everything was 2-1/2" but the last 18-20 inches of tails were 3-1/2" and that car was LOUD........
IMO...on the first couple seconds and the last couple seconds of this dyno vid I think the growling you hear is attributed to the huge pipes....it's like resonating.
http://s184.photobucket.com/albums/x258/svt32vdohc/?action=view¤t=MOV05351.flv
IMO...on the first couple seconds and the last couple seconds of this dyno vid I think the growling you hear is attributed to the huge pipes....it's like resonating.
http://s184.photobucket.com/albums/x258/svt32vdohc/?action=view¤t=MOV05351.flv
This is the answer you should pay attention to. NikwoaC got it right. Going down to 2.5 pipes is going to hurt performance and may not do enough for the noise. Check out different mufflers and you'll be happy.
Mufflers is the answer for sure....but going down to 2.5" tails isn't gonna hurt performance unless he was a lot of mods. On a stock-like/bolt-on 5.0L 2-1/2" should be all he needs.
I remember in the mid-late 90's they did a test on a custom built 2-1/4" off-road H-pipe vs. a 2-1/2" off-road H-pipe. The 2-1/4" pipe made more horsepower with an other wise stock 5.0L than the 2-1/2" did.
Thanks for all the comments gentlemen. My car makes 315hp to the wheels so I think a full 2.5" system should be fine. Biggest current problem is the fact that it makes women and children RUN!! I just called MAC and the 3" tails are NOT interchangable. So I would have to replace the entire tailpipe. Not sure the cost of the pipes as well as labor to weld them on is worth the small reduction in noise. For a little more a complete cat-back can be had.
I dont mind the flows, but I dont like the tails that come with the kit. They run straight out and dont follow the lines of the 1/4. Was also looking at the super turbo kit from dynomax and they only have one listed for the 94/95. Not sure it is a perfect fit on the fox or if the tails will look funny. If that kit fit nice, I would probably go that route. I like the dynomax tails and it would quiet down nicely as well. I have twisted wedge heads, F cam, off road X, track heat manifold... so even though the super turbos are a tame muffler, I'm sure they will make some noise with the rest of the combo and not scare people.
If anyone has used the 94/95 superturbo kit on a fox, please let me know how that went.
I dont mind the flows, but I dont like the tails that come with the kit. They run straight out and dont follow the lines of the 1/4. Was also looking at the super turbo kit from dynomax and they only have one listed for the 94/95. Not sure it is a perfect fit on the fox or if the tails will look funny. If that kit fit nice, I would probably go that route. I like the dynomax tails and it would quiet down nicely as well. I have twisted wedge heads, F cam, off road X, track heat manifold... so even though the super turbos are a tame muffler, I'm sure they will make some noise with the rest of the combo and not scare people.
If anyone has used the 94/95 superturbo kit on a fox, please let me know how that went.
315RWHP is a good amount on a fox. 2-1/2" should be fine. I don't think 3" would make it lose HP, but mayb not be necessary.
I've never used a 94-95 catback on a fox but I've used two 99-04 style kits. The tails were longer so I trimmed them down quite a bit. It bolted to the H-pipe just fine. I had to move the hangers to the bumper rebar as well, but you won't have to change the mounts on a 94-97 kit to a fox. 98 is when the moved the hangers to the top of the tail versus the side.
And also...my MAC kit from a 99-04 that I put on my LX notchback didn't follow the lines of the quarter...they went straight out.
MAC'n89Blckstng
Active Member
Hmm, thats wierd. I had a MAC cat back and went from 2 1/2'' tails to 3 1/2'' tails all the time with no problems.
Oh for sure! I love the OEM (angled) tail pipe look. I wanted that outta my car, but that's not the way that cat-back was set up.
I said that based on experiences I've had with different exhaust systems I've messed with. Usually on a given system if you do something to uncork it even more like going with larger diameter tubing it tends to mellow it out a bit from what I've noticed. True, the mufflers are going to have the greatest effect on noise level, and every setup is different, but pipe diameter can change sound. Maybe not from a decibel standpoint, but tone will change depending on pipe diameter. If you decrease pipe diameter while airflow remains constant the tone is going be higher. If you increase pipe diameter and slow down the air it is going to sound deeper and more mellow. That being said, I don't know that a 1/2 over a short distance is going to make a huge difference audibly, but it will change the way it sounds a bit. It will definitely not have the desired effect the OP is looking for.
Kinda like exhausts on V6's. Bigger is usually throaty and smaller is usually raspy. I can see that I guess but I think he needs to just swap a 2.5" cat back and be done with it.
I also like the exhaust to follow the 1/4's. Nothing a few minutes with a torch or a few dollars at the exhaust shop can't fix. A slight bend is all that is needed.
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