i screwed it up cuz i didnt go for the thin wall pvc. and im not gonna attempt stretching my filter to fit 5/8" more than its suppose to. i plan on a 4" polished aluminum...at sum piont. i have it rigged up nice with the stock tube...and it barely has any bend to it. the pcm and filter are both secure. and it sounds great so im saticfied for now.