Complete Exhaust Change & I mean COMPLETE....w/n
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Joined: Aug 1999
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From: CA
Complete Exhaust Change & I mean COMPLETE....w/n
Well it was brought up to my attention that there is a set of headers for the 2.8L and it looks like I'm going to get them. Well this is what I want to do: headers (obviously), complete new exhaust piping made out of aluminum, and maybe a higher flowing CAT. THis is what I want to know: 1) should I go w/ a larger diameter exhaust piping for the entire exhaust if so what size larger than stock?, 2) should I just leave the CAT on or get a larger high flow CAT and if so what size & brand?, 3) Would this make my car sound meaner?
By the way this is for a 2.8L V6 on an '86 Firebird & the Headers are Hooker Steel Headers. Later
- Mike Harvey -
By the way this is for a 2.8L V6 on an '86 Firebird & the Headers are Hooker Steel Headers. Later
- Mike Harvey -
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Joined: Sep 2000
Posts: 118
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From: Memphis,Tn
Hey Mike,
I f i were you i would go with 3" exhaust all the way back.If your cat isnt too old and if it is already high flow i would keep it on.Just my .02.Also,what are you going to bout your muffler.Are you keeping your flow,also if you put on another cat i might want to buy your cat!
I f i were you i would go with 3" exhaust all the way back.If your cat isnt too old and if it is already high flow i would keep it on.Just my .02.Also,what are you going to bout your muffler.Are you keeping your flow,also if you put on another cat i might want to buy your cat!
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Joined: Aug 1999
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From: CA
One question though. Most aftermarket CAT back systems are 2.5", if I were to go to a 3" exhaust piping all the way back wouldn't that destroy all the back pressure that the engine needs for the valves and all that crap? I just wonder if my car would run to free flowing with the exhaust outlets so wide plus I would probably be buying a 3" CAT too. Let me know & also I will be getting a new CAT too. Nothing wrong w/ the one I got only thing is that it is a stock regular CAT. Later
- Mike Harvey -
- Mike Harvey -
Senior Member
Joined: Jun 2000
Posts: 712
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From: Los Angeles, Ca, USA
Car: 90 Camaro RS
Engine: 305 TBI
Transmission: T56
well according to federal law...you cannot modify or swap out your cat unless it is malfunctioning.... 
LOL anyways...backpressure smackpressure....its bologna...its like the blair witch....it doesnt exist...anyways...you cant go wrong with 3 inch exhaust...a LOT of companies offer 3 inch cat back systems...which are better than 2.5...which is usually stock. since youve decided to change out the cat...look at the prices of Random Technology Hi FLow cats...the best on the market...then come back to me and ill sell you mine...its brand new...i have no use for it anymore....i bought it 3 weeks ago...and never installed it...cuz my headers are not emissions legal....anyways...hookers are a great brand of headers....you should be good without coating them...unless the elements are Real bad where youlive....coating is expensive. hooker makes a great flowing cat back or you could go with flowmaster like everyone else...LOL...anyways good luck
------------------
Rick
90 Camaro RS 305 TBI
400 small block, Hooker 1 3/4 super comp long tubes, Random Tech Cat, Hooker aero chamber cat back on the way!!
TH700-R4 with Trans-Go shift kit
MacEwen Motorsports White Gauge Overlays
K&N Filter Charger (wooohooo)
GTS Headlight and Taillight covers
5% Limo Tint all around
Classic White Chevy Bowtie sticker on rear window
www.geocities.com/esvalenz
Man if my camaro were a rice-rocket all those mods would give me what...easily 50-60 hp!!!
LOL anyways...backpressure smackpressure....its bologna...its like the blair witch....it doesnt exist...anyways...you cant go wrong with 3 inch exhaust...a LOT of companies offer 3 inch cat back systems...which are better than 2.5...which is usually stock. since youve decided to change out the cat...look at the prices of Random Technology Hi FLow cats...the best on the market...then come back to me and ill sell you mine...its brand new...i have no use for it anymore....i bought it 3 weeks ago...and never installed it...cuz my headers are not emissions legal....anyways...hookers are a great brand of headers....you should be good without coating them...unless the elements are Real bad where youlive....coating is expensive. hooker makes a great flowing cat back or you could go with flowmaster like everyone else...LOL...anyways good luck------------------
Rick
90 Camaro RS 305 TBI
400 small block, Hooker 1 3/4 super comp long tubes, Random Tech Cat, Hooker aero chamber cat back on the way!!
TH700-R4 with Trans-Go shift kit
MacEwen Motorsports White Gauge Overlays
K&N Filter Charger (wooohooo)
GTS Headlight and Taillight covers
5% Limo Tint all around
Classic White Chevy Bowtie sticker on rear window
www.geocities.com/esvalenz
Man if my camaro were a rice-rocket all those mods would give me what...easily 50-60 hp!!!
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Joined: Oct 1999
Posts: 2,977
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From: Davison / Troy ,Michigan
Car: 1991 Pontiac Firebird
Engine: 3.8
Transmission: 700r4
Axle/Gears: Dana 60
I agree with the post above. 3" is just to much for a 2.8L engine. I would try maybe 2.5" but nothing above that. And yes I would coat your headers if I were you. I coated mine and I love it. And backpressure is not a myth.
------------------
Eric Natzke
91 Firebird 305 TBI (ZZ5 summer of "01")
ASCD Ram Air Hood-3" custom exaust-Flowmaster 80 Series-No Cat-Edelbrock TES Headers (coated)-March Pulleys-TBI Spacer-K&N Open ELement-TransGo Shift Kit-B&M Supercooler 28,000 GVW-Hypertech Thermomaster-160 Stat-3:42 GM Gears-Auburn Posi Unit-Edlebrock Strut Tower Brace-MSD Superconducters-MSD Cap & Rotor-MSD Blaster Coil-Rapidfire Plugs-265/50/R15 Tires-Emmison's all Gone
http://members.aol.com/j007golden/91firebird.html
For info on certain parts or mods go to the site below
http://members.aol.com/j007golden/modeval.html
Exhaust manifolds work as well as they do for off-idle torque because they use the "expansion" principle. The hot gas comes charging out of the port and sees a wide open common chamber to spread out in. That acutally works better at low speeds than headers. As the RPMs increase though, the lack of direction causes a lot of turbulence and the stock manifold becomes a hinderance.
With headers, the exhaust slug has to push the long column of gas in the header tube out of the way as it comes out. At higher RPMs, the header pipe can take advantage of the inertia of the moving column of gas to scavenge the rest out and "pull" the intake charge into the cylinder. There is an RPM range at which the pipe "resonates" and that is where headers shine.
With headers, the exhaust slug has to push the long column of gas in the header tube out of the way as it comes out. At higher RPMs, the header pipe can take advantage of the inertia of the moving column of gas to scavenge the rest out and "pull" the intake charge into the cylinder. There is an RPM range at which the pipe "resonates" and that is where headers shine.
Eric Natzke
91 Firebird 305 TBI (ZZ5 summer of "01")
ASCD Ram Air Hood-3" custom exaust-Flowmaster 80 Series-No Cat-Edelbrock TES Headers (coated)-March Pulleys-TBI Spacer-K&N Open ELement-TransGo Shift Kit-B&M Supercooler 28,000 GVW-Hypertech Thermomaster-160 Stat-3:42 GM Gears-Auburn Posi Unit-Edlebrock Strut Tower Brace-MSD Superconducters-MSD Cap & Rotor-MSD Blaster Coil-Rapidfire Plugs-265/50/R15 Tires-Emmison's all Gone
http://members.aol.com/j007golden/91firebird.html
For info on certain parts or mods go to the site below
http://members.aol.com/j007golden/modeval.html
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