Exhaust suggestions

[rafael martinez jr]

hi i have a 80 malibu that i just put in a 5.3 ls motor with 80,000 i replaced the rod bolts with arp and the oil pump and timing chain. replaced the oil pan that has a trap door with pickup ls7 lifters new cam 604-610 lift arp studs i pickup a set of 862 heads that have been ported and bigger springs,and 2.00 intake valve victor manifold long tube headers. a friend told me to run a 2-1/2 in exhaust rather then the 3in i was goin to use with the mufflers in front of the rear with turn downs he said i might lose bottom end with the 3in any ideas also running a turbo 400 manual valve body with a trans brake 2,800-3,200 stall 3.50 gear and some nos

 

[pontiacgp]

here is the law in Ontario for tailpipes

“no exhaust system shall be shortened or modified from original equipment so as to fail to direct the exhaust beyond the underbody of the occupant compartment or luggage compartment, and in no case shall the distance between the outlet and periphery of the underbody, past which it directs the exhaust, exceed 15 centimetres.” (6"). I doubt there is room behind the red circle to keep the tailpipe 6" from the corner of the door

 

[fleming442]

If you use a straight through style muffler, it shouldn't be that much difference between 2.5 and 3. What do you plan on zinging it to, 9000?

 

[bracketchev1221]

I think the mufflers matter more than the exhaust size. I had a 540 hp 427 in my Chevelle many years ago. I put a 2 1/2" exhaust on it with Walker Dynomax super turbo mufflers to quiet it down. Well not only did it quiet it down it choked it. I knew I was in trouble at the track when I went to put it on the transbrake and the engine almost didn't make it to the rev limiter before the tree went green. Then I noticed the engine took forever to hit the shift point of 7200 rpm. Well the car ran 12.05. I took the exhaust off and went back to open headers and ran 11.27 on the next pass.

 

[rafael martinez jr]

im not spinning it at 9,000 has for the tail pipes dont if im going to use it cause the car is for cruising and some times track or street racing and bracket chevy thats a awesome run 11.27