Hi,
If you are going with 2" primaries or larger, you are aiming for top end power. I just want to point that out. The bottom end will suffer. Maybe you know this, but I didn't until recently. 
Mike
Mike, that isn't allways the case. Headers are one of those "combination specific" items that needs to be closely evaluated when sorting out the build. For example : My 446 made the same hp (535) with a 17/8 & 2in primary tube header. The torque, however was down 20ftlbs across the board, with the 2in tubes. In this case the 17/8in header was the "correct" size because it maximized peak torque and it didn't hurt any of the top end power.
Throw a stroker into the mix and it's a whole new ballgame. A small primary tube will bring the peak tq to a lower threshold and that will in turn limit top end power. Essentially, the engine's output can be limited by too small a header.
The original poster is looking for a 2in-21/8in tube for his engine. That is the correct size for this type of application based on what i've seen on the dyno with those types of builds.
Ron
