bought headers and y-pipe (match set)
y-pipe is 2.5 inches and i have 2.5 on the car right now but i built a 383 and wondering if i should go bigger????
should i cut the y-pipe where the 2 pipes come together and put 3 inch or just leave it.
the motor will not pass 5500rpm
the cam has .480 lift and 110 duration

thanks

 

I think you should. That 2.5 is really small for a single but you probably already know that. And being that close to the headers I would think has a potential to really slow the exhaust down. I also got a header/y-pipe combo and it turned out to be 2.5 inch. It was the hedman package. The y-pipe I pulled off my car looked bigger in diameter.

So anyway are you doing the cutting and welding yourself. If so can you tell me how you plan to do it since I want to do the same.

 

If I were you Id send back the ypipe and custom make one w/a flomaster ypipe. (or have it done that way) that way you can have the main ypipes in 2.5" diam. and the single pipe in 3".

why did you use such a small cam in a 383? and why so low rpms? you should be able to go for 6K no problem and not worry about premature wear on the internals. thats kind of like building an eng. to make 500 HP but then adj. the throttle to only go 3/4 the way open. I dont see the point but thats just me.

chris

 

You should be running at least a 3" system or duals.

 

I'd go for a set of 1 3/4 SLP headers and a 3 in exhaust. Not to mention that the cam is a little flat for a 383. My lift is at 560