what size exhaust should i run

[tstang93]

I just got my block back from the machine shop its a 351 W stoked out to 408.The exuahst system i have now is 2 1/2" all the way out the back no cats x pipe 2 1/2"offset flowmasters 2 chamber and flowmaster 2 1/2" tail pipes.
Is there a folmula to figure out you exahust size i think this is perfect what are you guys running.
I"ll prob put on some cut outs that i can remove at the track
Oh and another question for anyone what size primary should my header be I've got a set of shortys bbk 1 5/8 on the 302 in it will these work on the 351 heads
Tony

 

[tstang93]

any one know about the headers or what do ya just guess or put the biggest ones on or what

 

[Haus]

how much HP are you expecting??

 

[nunly94gt]

We built a 351w one time in a 94, it started with 2 1/2 from the 302 but ended up cutting back the long tubes and making it 3" all the way. The old was way to restrictive and the car got some life when it was changed. So IMO atleast 3".

 

[tstang93]

i would like to an honest 500 hp do the headers for the 302 fit the 351 heads i'll prob stick with emfor a while if they do

 

[351GT]

I have a 351W in my 93. I used hooker shorties for the 351 swap. Im not sure if the 302 will work, but I dont thinks so. I had 2 1/2 h-pipe and 2 1/2 3 chamber flowmaster. Im in the process of changing it to 3 inch all the way back. Go 3 inches for sure.