custom exhaust questions
03-27-2009, 01:39 PM
#1
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custom exhaust questions I went to a custom exhaust shop that I live close today to get a quote on a custom catback. They were really busy and asked me to come back in an hour. The guy looked at my car and did'nt seem to know too much about F-bodies in general, he even asked me "what engine size is this?" He was telling me that I would see the biggest gain from a high flow cat, I told him I just want to change the pipe size, muffler and tips. This guy is'nt stupid I've talked to him before, he's older and alot more familiar with old muscle cars. Anyway what do ya'll recommend for just the catback (pipe size, muffler)? I'll be doing headers and a y-pipe hopefully this summer. Should I get rid of the stock cat? Will it make much of a difference? I know I want Corsa style tips, but whats a good muffler to go with? Or no muffler at all? lol
03-27-2009, 01:45 PM
#2
The stock cats flow great, id either keep the stock ones or not have any cats at all. By the way there 2 cats on your car....in a relaticely stock car the stock i pipe flows enough to keep up with what the engine puts out. If i were you id just weld in a nice flowing muffler(hooker,magnaflow,etc) and call it a day. This will work fine until you go big cam/heads
03-27-2009, 02:03 PM
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so the only really restrictive thing is the stock muffler? No need to go with bigger pipe? I doubt this place would let me drive off with no cats because it is also an official inspection station
. I want it decently louder than stock but not so loud that when I do headers later it will be insane
. I want it decently louder than stock but not so loud that when I do headers later it will be insane
03-27-2009, 02:17 PM
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Have some nice tips welded on the stock catback and put an electric cutout on the I-pipe. That way you can be really quiet and really loud at the flick of a switch.
03-27-2009, 02:24 PM
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I was thinking about that but I'd be worried about ground clearance for the cutout because I know I'm eventually going to lower the car 1"-1.5" something like that and the roads suck here. That would be sick though hmmm...
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03-27-2009, 04:07 PM
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The stock cats flow great, id either keep the stock ones or not have any cats at all. By the way there 2 cats on your car....in a relaticely stock car the stock i pipe flows enough to keep up with what the engine puts out. If i were you id just weld in a nice flowing muffler(hooker,magnaflow,etc) and call it a day. This will work fine until you go big cam/heads
03-27-2009, 09:37 PM
#10
Opinions vary- they flow a ton better than cats back in the day...and by looking at his mod list either no cats or leaving the stock cats would be fine for him. Buying a high priced aftermarket cat is not going to net him a great performance gain for the money. So there for the stock cats flow great for whats hes doing right now.......
04-08-2009, 07:28 PM
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Define you power goals and stick to what works.
If you are planning on staying at stock power levels and not going LTs:
- Replacing OEM cats on stock power level vehicles with stock manifolds is good for 5-8 HP at best. Straight piping them or hollowing them out provides little more than high flow cats. There are other reasons for replacing cats if other modifications deem it necessary, but again on typical stock power vehicles your money is better spent elsewhere.
- A good flowing aftermarket muffler in place of the OEM is solid 10-15 RWHP mod. Replacing the 2.75" stock cat-back tubing with 3.00" is good for another 5 HP coupled to a good flowing muffler.
If you are planning LT's the stock cats are a non-issue as most will require a new y-pipe. Again keep in mind your goals and size accordingly. LT headers, a catted 2.5" y-pipe and 3" cat-back will support a 425+ rwhp with little power detriment and still have a reasonable performance exhaust note.
If you are planning on staying at stock power levels and not going LTs:
- Replacing OEM cats on stock power level vehicles with stock manifolds is good for 5-8 HP at best. Straight piping them or hollowing them out provides little more than high flow cats. There are other reasons for replacing cats if other modifications deem it necessary, but again on typical stock power vehicles your money is better spent elsewhere.
- A good flowing aftermarket muffler in place of the OEM is solid 10-15 RWHP mod. Replacing the 2.75" stock cat-back tubing with 3.00" is good for another 5 HP coupled to a good flowing muffler.
If you are planning LT's the stock cats are a non-issue as most will require a new y-pipe. Again keep in mind your goals and size accordingly. LT headers, a catted 2.5" y-pipe and 3" cat-back will support a 425+ rwhp with little power detriment and still have a reasonable performance exhaust note.
04-08-2009, 10:58 PM
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^ is right, not a whole lot of HP to gain by removong cats on a stock car, BUT it is definately worth it for sound. Cats make it sound like crap.
Replacing just the muffler will give you sound also,and a few HP, stay away from a flowmaster though. The stock I pipe is 2.75 I believe, and is efficient on most cars that are relatively mild..Probly no HP difference over a exhaust shop 3in kink bent tubing, the stock i pipe is stainless and mandrel bent.
Any of the cutouts you buy will clear fine even on a lowered car if you place them under the rear seat area.
If you are running a cutout w/ cats still, please don't, it will sound like a dualed out truck!
Replacing just the muffler will give you sound also,and a few HP, stay away from a flowmaster though. The stock I pipe is 2.75 I believe, and is efficient on most cars that are relatively mild..Probly no HP difference over a exhaust shop 3in kink bent tubing, the stock i pipe is stainless and mandrel bent.
Any of the cutouts you buy will clear fine even on a lowered car if you place them under the rear seat area.
If you are running a cutout w/ cats still, please don't, it will sound like a dualed out truck!