Which Y pipes are interchangeable between headers? More specificly, will a pacesetter Y work with the new flowtechs, hookers, or jethots?

 

nope

 

Flowtechs are flanged so they won't fit anything else but Hookers and Jet Hots are very similar so they might be easily interchangeable...Pacesetters are slip on as well but the header length/collector differences might prevent it's Y-pipe from fitting Hookers/Jet Hots and vice versa I would assume.