My friend with an NA 87 wants the same setup as me. Now I got 3" all the way...3" splits as well to 2 mufflers. Now he wants the same setup, but would 3" on his NA be too big?

 

Come on someone?...can't be that hard a question...NA guys, were you at?

 

A 3" main and a 3" Y?
Whats the point of a Y that large, when the main is the same size?
Ideally, you want the exhaust to get somewhat smaller in diameter towards the rear of the car, to maintain the velocity of the xhaust flow while it cools towards the end of the pipe.

I have heard many opinions os sizes. I have a street ported N/A, with a 2.5 into a 2 inch Y. All straight through mufflers. It may be a little small, but I can easily make another one. I can't see the 2" Y as being the restriction though, since a 2" pipe has a volume of 3.14 "^3, (doubled- two pipes- so 6.28"^3) and the main pipe only has a volume of 4.9"^3.
A 3 inch main has a volume of 7"^3 though- which makes a better match for the 2" Y.
A question- how come there are 2 1/2 inch Y's available for N/A's, but only 2.5 inch main pipes???
Doesn't make sense to me- It will only flow as much as it's smallest part, no matter how short it is.

 

I have single 3 1/2 inch splitting into dual 2 1/2 or 3 i forget
with 4 inch tipped stainless steel mufflers.

i gotta go measure it