[04gtdrop]

ok, im pretty sure that my driver side cat is bad. and i was thinking about just getting new legs for my pro chamber and running no cats.

now i know its illegal to do so here in CA, but im thinking about 2 things

1st how loud will it be? i got a 2004 gt 5 spd, with a mac prochamber with 2 hi flow cats right now and a mac cat back. i used to have a 95gt that had an old school flowmaster catback and an o/r h pipe and that F***er was LOUD, some times too loud with the drone. anyone know bout how loud my 04 would be w/o cats?


2nd how will the no cats impact my MPG? it killed my mpg on my 95. and right now im getting about 17-21 on the freeway.

thanks SN

[99GTtony]

Shouldn't be too bad without cats. I have a non-catted one on mine with MganaFlows. It's actually very mellow at idle, but sounds good in the low rmp ranges. If you do a lot of freeway driving it may get on your nerves having one constant sound. I haven't noticed any difference at all on my MPG. Here's a small clip of my exhaust. Takes a few seconds to load. No rev above 3k.

http://media.putfile.com/99-GT-exhaust

[stng]

I dont think it will have any impact on your mpg cats vs no cats, hasent affected mine...
As far as the noise obviously it will be louder, but too loud? I doubt it... From the exhaust clips I have heard the prochamber w/o cats isnt as loud as an H-Pipe w/o cats. I have never heard any exhaust clips with a catted prochamber, but off road ones sound the best of all the exhaust clips I have heard, I wish I had bought one...
Where I live you only have to deal with cali emissions when you sell/buy a car so too me that has never been in the equation, but if you live somewhere with more strict emissions laws you may just want to go ahead and replace the cats...

[Blinkstang]

Yeah you will be fine with an O/R Prochamber in the sound department. I had an O/R Prochamber with Magnapacks and LT's and it sounded very deep and had a great tone, just wasnt loud enough for me. It also didnt drone with my Packs, had a very nice consistent sound to it.

[04gtdrop]

Originally Posted by 99GTtony

Shouldn't be too bad without cats. I have a non-catted one on mine with MganaFlows. It's actually very mellow at idle, but sounds good in the low rmp ranges. If you do a lot of freeway driving it may get on your nerves having one constant sound. I haven't noticed any difference at all on my MPG. Here's a small clip of my exhaust. Takes a few seconds to load. No rev above 3k.

http://media.putfile.com/99-GT-exhaust

crap, im at work and they dont have quick time on these computers. and it wont let me install quicktime... i cant listen to the clip. if you have it in a Windows media player format then i could watch it....

[04gtdrop]

ok, so i called mac and they have both catted and non-catted legs for my pro chamber. The one side with the cat is 150.00 OR i could get both legs without the cats for 75 each which is 150.00!!!!! I really need to order these today or by tomorrow at the latest.... can i get some votes in here? which ones do you think i should go for?

i do some freeway driving, but its only about 20-25 miles one way (the other way is bumper to bumper so even though its freeway, its like being on the streets, never get past 3rd)

the rest is street use. i do about 250 miles every 3-4 days.

i'm just worried about a bad drone. i like it loud, and i like it deep... i just dont like the drone that my 95gt had...

any thoughts??? thanks SN

[99GTtony]

Personally if you want the sound, you need to lose the cats. But I know CA is very strict on its emissions testing. Here they dont use a sniffer if you have a computer controlled car. They just plug into my OBDII port, it shows no codes. So it passes. Do the sniff all CA vehicles?

[04gtdrop]

Originally Posted by 99GTtony

Personally if you want the sound, you need to lose the cats. But I know CA is very strict on its emissions testing. Here they dont use a sniffer if you have a computer controlled car. They just plug into my OBDII port, it shows no codes. So it passes. Do the sniff all CA vehicles?

yes they do, but i have the stock H-pipe out back, so if i need to i got put it back in for the sniff test... as long as i dont get cuaght on the road by a cop. i'll be good....

i'm more worried about how it will sound (i.e. too much drone)

and

MPG

[99GTtony]

My MPG actually improved after my install, and adding my Predator. Well at least if I keep my foot out of it. I dont see how the cats will affect you MPG, but I'm no mechanic. Mine doesn't drone unless I'm on I-5 running right at 65. Any slower or faster and it sounds fine. Guess it's just that certain RPM that wil make that sound.

[04gtdrop]

hmm ok... 99tonygt.... what rpm are you at when your doing 65?

cuse i got 3.73's so....

[propellerhead]

If you buy the entire off-road H, keep the off-road legs, and I'll give you $40 for the H.

[99GTtony]

it's a little above 2k at 65. with 3:73's you'll be pulling a higher RMP I think?

[04gtdrop]

Originally Posted by 99GTtony

it's a little above 2k at 65. with 3:73's you'll be pulling a higher RMP I think?

yes, i dont know the exact mph at 2k, but i do have some drone already from like 1,900- 2,400 rpms

[1BAD93]

I'm dragging this back up cause i have a related question. I had my catted pro-chamber installe d afew months back and after about a month or so i started getting a drone/vibration from about 3100 - 3200 rpm in any gear and its only lasts for a couple hundred rpm. Has anyone had this issue. I'm wondering if its one of the cats gone bad or if tis just normal for the pro-chamber. Any ideas?

Joe