318 exhaust size
Simply put, just to much of a good thing isn't a good thing.
With the headers into the exhaust pipe into the muffler, the collector becomes to long and it lost the pressure wave tuning. The muffler used is just like extending the exhaust pipe.
A stock/near stock 318 is often best with a 2-1/4 exhaust pipe w/a H or X into a turbo muffler. If you could put the muffler closer to the header that would be preferred since the power level is low with small cam size.
This is what I have personally found.
If you can make it sing better with a 2-1/2, go for it and share!
