im planning on welding a custom header back exhaust system for my 79. what size exhaust piping would you guys suggest for a stock port/street port 12a w/ a weber? im thinking anywhere between 2.25"- 2.75". tell me what y'all think is a good size.thx

 

2.25 dual to one muffler. above that, it will be too loud. smaller will be too restricted. btw, there is big difference between stock and street ported 12-A. so which one is it.

 

wackyracer, those look like some huuuge honkin exhaust ports in your lil picture deely. im interested to hear about it if its yours but if it is just a pic from somewhere else no worries.

 

i wanna make the exhaust system now, large enogh to be effective for use on a street port and later on i will have the motor ported, but i just want to get the exhaust out of the way and get some power out of it in the mean time.btw, any reason for smaller duals as apposed to a larger single?

 

Use 2.25" piping. Anything larger than 2.5" is reserved for bridgeport/peripheral port or turbo. I went 3" on my car. Its a mostly stock 12A, no porting or anything like that. I have been told that I have actually lost power because of it.

 

2.25-2.5 would be my recommendation. 2.5 isn't so big that you lose power.

 

one 2.5" pipe, or dual 2"

 

thx for the info. i think im gonna go for a single 2.5", ive always liked the look of a large single tip(maybe a dynomax ultra flow) plus if the exhaust holds up over time i could use it for a turbo'd 12a