Would 3 inch pipes affect the back pressure for our L03 engines. Or should i just put 2 1/2 inch pipes on. What would happen if i did put 3 inches on????? Would i loose and performance??? Any comments would be appreciated...... THANKS

 

I put 3" cat-back on my '92 RS. I didn't notice much power difference. I noticed the biggest difference in my gas mileage. It went from about 19.5 to about 19. Not a big drop. I think it was from the loss of torqe from backpressure. That caused me to start to give it more gas on acceleration in daily driving. Now that I've gutted my cat im down to about 16.5. That's a considerable amount. Hopefully the SLP headers I just bought will help a lot with the power. I'm waiting for $$ so I can send them to Jet-Hot.

 

You won't loose any performance, it might make it sound different though. Should be deeper. When you say tailpipes, what are you talking about? The intermediate pipe from the cat to the muffler? or the tailpipes that come of the muffler?
------------------
1989 Pontiac Firebird Formula LO3 Auto
-180 degree stat
-Hooker Cat-Back
-vinyl security shade, velcro t-top bag
*****Possible summer '01 mods*****
Dual Snorkle, Auburn Posi, Keyless Entry, Wonder Bar from my IROC, 4th gen seats, T/A tail lights

http://www.geocities.com/krt80/

[This message has been edited by Keith5 (edited March 05, 2001).]

 

Naa i meant the pipes coming from the engine to the muffler. because i was debating on whether to put 2 1/2 or 3 inch. Start from the y-pipe to the muffler. What do you guys recommend for a Hi-flo cat. THANKS

 

Hmmm, does this belong on the tbi board?

Moving to exhaust where everybody knows exhaust.

 

Get the three inch pipe. You may thank yourself in the long run. Not to mention is sounds GOOOOOD!

------------------
89 Formula 305 TBI
160* stat, 200* fan switch, K&N, Headers, 3in Flowmaster (hollow cat) back, pullies, 1.6 full roller rockers, B&M trans cooler, home-made ram-air
3.73 Richmond gears and SLP Zexel Torsen Posi (waiting for install)

 

I GOT THE FLOWMASKET 3" SYSTEM AND I DIDNT NOTICE ALOT OF PERFORMANCE GAINS UNTIL I ADDED THE EDELBROCK TES HEADERS BUT I DEFINITLY RECOMMEND THE 3" iT HAS MUCH BETTER TONES AND (BACKPRESSURE ISNT AN ISSUE) THEN 2.5 " PIPES.

------------------
91 camaro RS
- 305 TBI
Mods: Performer tbi intake, 1" TBI spacer, K+N, jet fan switch ,160 thermo, accel control module, Jet Stage 2 chip, edelbrock TES headers, Compleate 3" Flowmaster exhaust, Edolbrock springs, KYB struts and shocks

Soon to come . Posi 323 rear end , SLP boxed LCA's and panhard bar, ascd ram air hood, Z28 spoiler, white guage faces.