Since I am making my own headers from scratch, I couldn't show you guys how easy it is to use RWD headers (for a 2.8/3.1/3.4) on 3x00 heads.
Well I had a chance to modify a set for a GrimmCS...







Used a die grinder and 4 flute 1/4" ball endmill. It took about 15mins per header, if that.
Biggest thing is to make sure the inner diameter of the headers isn't smaller than the ports. As you can see in the pics, the gaskets are smaller than the ports, and almost perfect on the headers.

 

Hey...I remember those
Are those the 3500 heads?

 

3400 heads and 3400 gaskets, but the 3500 bolt pattern is the same.Iin fact, those are the new gaskets going on mine.