Does a d-port header make any difference? Like the hedman 68469. I plan on getting some different heads down the road and the ones I've seen have all sorts of port shapes. Needless to say, I'm quite confused. Educate me please.

 

Heads with D-shaped exhaust ports usually flow better than heads with round exhaust ports. They're also raised higher on the head than round ports. Your header choice will need to make sure they cover the raised exhaust port completely. That usually means using 1 3/4" headers.

 

OK, thanks. I think I'll go with the round and then when I get new heads I'll fab something up to cover the ports and go into the headers. I don't want 1 3/4, too big.