probably because it would bleed off too much compression...and you don't start making power til 3K or so...i wanted to get the 509 when i was informed only by chevy guys when i was 16 on what to do with mine...glad i waited and did my research.

i really can't wait to get mine back together. the XE268 is pretty popular as it uses stock converter and is still supposed to have a bit of a lumpy idle.