Anyone know what diameter the dual cat y-pipe is before the converters? Is it 2.25"?

 

I assume you are talking about the H.O. 350 package (because it has the dual cats). I checked the GM Performance Parts Catalog on line and it said the kit comes with high flow exhaust manifolds with 2.25" outlets, a single 3" diameter tail pipe and a transverse muffler. I hope that helps.

 

very nice car Acceld Z!!

 

Thanks guys