I have been preaching the BTM for years!! The restriction in the stock exhaust isn't the size of the exhaust, it is the factory muffler. My EGT's dropped 100-150 degrees between the AIS/BTM install. Place a 5/8 garden hose into a 6" drainage pipe and it ain't going to flow any more water, but most feel warm and fuzzy by replacing a perfectly good exhaust system. To the OP, I would have it welded in if you haven't already, I'm not a big fan of clamps.
NCH