I have lots of that laying around. What would be the best size?

Thanks.

Brad...

I've been giving some thought to using square tubing for the headers. It's strong and would be easier to cut holes for the pipes to weld to and may be able to mount the turbo on it somehow. Hmmmmmm........

Brad...

It's much bigger then the passages in even the 'good' (tpi/L69) exhaust manifolds (never got why people made a point of saying that these are better then the standard 3rd gen V8 manifolds since both are the same past the down pipe connection and the biggest restriction in both is the same), and I'd bet that it's bigger then the tightest part of the banks manifolds (Andris is probably the only one that could really confirm that here...).

My collectors neck down to 2.5" right now and I'm thinking of using short pieces of 2.5 or 2.25" to connect to the turbo flange.

T3 turbine inlets have almost exhactly the same area as a 2.25" tube (although if you measure around the square opening you'll find that it's almost exactly the same as the circumference of 2.5", so if you use 2.25 you'll either have to blend the opening some with a grinder or stretch it a little) so unless you've got a lot of bends, you're not gaining anything by going larger but increasing volume/slowing spool...