I'm about to get a Cattman Y-pipe, and I need to know what size pipes would work the best in conjunction with this. I was thinking 2.5" from the cat, but would 3" be better? What are the ups and downs to these? Also, I'm trying to decide between lowering springs. I'm stuck between Tein S-techs and Progress. Any suggestions would be awesome. Thanks.

 

are you on boost?because if u are than it owuld be better to go 3 in diameter but if your car isn/a do the 2.5 becuase you will nedd the back presure created by the cats and the smaller piping

 

i was wondering if i was gonna get an answer. i almost gave up on it. thanks for the help. i'm going with 2.5"