Based on DC's site, I'll be going with a 4-2-1 header, probably ceramic coated (why would you pay more for stainless when you can have ceramic????)... but they don't list the reasoning behind having 1 and 2 piece headers.

What's the reason and which should I get?

 

purely easy of installation, though some may say that the one piece is better preformance its too smallt to notice or even notice on the dyno at all.

 

Thanks for the info, I had a fealing it had something to do with that. I'm looking for power increases across the board with no loss of torque (I'm looking for as much TQ as possible) so it appears the 4-2-1 is for me... at least that's the way I'm reading DC's site...

 

You should really try using the SEARCH feature at the top man. I've browsed at least three of your topics so far that could have easily been solved with a simple search