Exhaust and header question
Thread Starter
Instructor
Joined: Sep 2001
Posts: 128
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From: Pittsburgh PA
Exhaust and header question
These are probably silly questions to most of you, but how much of a horsepower increase would I see from a stock engine (1991 L-98)with a Flow Master Cat Back exhaust installed? I want more power and a nice low growl. Also would changing the headers help me gain more horespower as well? I was looking at the TPIS header kit. What kind would you suggest?
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
Re: Exhaust and header question (Lexdog)
I'm not knocking Flows (the ForceII system was on my car for a coupla years) it's just that my muffler guy made a good point to me awhile back:
Flows are some of the more restrictive "perf" mufflers. BTW, he sells them. He recommended Magnaflows since they are what's known as a "straight-thru" muffler. No back pressure. Flows have baffles and chambers=back pressure. I know some is good, but in my case, I drive in Ca. and already have the restiction of 3 catalytic converters.
I took the Flows off 2 weeks ago and just have NO mufflers on right now. The exhaust tone stayed pretty much the same. Only a little louder. That's to say the Flow 3 chamber that is "designed" for our cars sounds kinda deep. Lots o' people love them. I wanted a 2 chamber sound.
I ported my stock manifolds as I had to retain smog fittings(couldn't find headers for our cars with these fittings) There is alot of factory slag in these things!
I also welded into the pipe right before the pass. side pre-cat, another O2 sensor bung for tuning purposes. The A/F ratio meter's sensor goes here.
Flows are some of the more restrictive "perf" mufflers. BTW, he sells them. He recommended Magnaflows since they are what's known as a "straight-thru" muffler. No back pressure. Flows have baffles and chambers=back pressure. I know some is good, but in my case, I drive in Ca. and already have the restiction of 3 catalytic converters.
I took the Flows off 2 weeks ago and just have NO mufflers on right now. The exhaust tone stayed pretty much the same. Only a little louder. That's to say the Flow 3 chamber that is "designed" for our cars sounds kinda deep. Lots o' people love them. I wanted a 2 chamber sound.
I ported my stock manifolds as I had to retain smog fittings(couldn't find headers for our cars with these fittings) There is alot of factory slag in these things!
I also welded into the pipe right before the pass. side pre-cat, another O2 sensor bung for tuning purposes. The A/F ratio meter's sensor goes here.
Team Owner
Joined: Sep 2001
Posts: 62,142
Likes: 1,729
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Exhaust and header question (89 Paul in cal)
Flowmaster seem to be more restrictive like he said, good sound but not enough CFM. I like Power Effects, Borla, B&B TriFlo.
TPIS headers are good, i'm gettin em
[Modified by vader86, 4:42 PM 1/22/2002]
TPIS headers are good, i'm gettin em
[Modified by vader86, 4:42 PM 1/22/2002]
