Ive been debating with myself for a while now...i sold my Injen Ses because i didnt really get any power out of it so i became disapointed now i just ordered a magnaflow muffler for a good price and im going to do the piping next week...My question is im going to go from 2nd cat to muffler but should i go 2.25 piping or 2.5..most of the cat backs that are out are 2.5 but im afraid of losing to much backpresure...what do u all think

 

Try 60mm.

 

don't worry about backpressure - here is a little test of axle backs we did a couple of weeks ago

note the dyno graph of us running no exhaust at all - still picked up everywhere in the power band

https://www.scionlife.com/forums/vie...070&highlight=




here is the graph for the lazy

002 - green - stock axle back
003 - blue - no axle back

 

2.25 if you're naturally aspirated 2.5 if you're going FI

 

i'd go 2.5" for NA and then 3in minimum for forced induction.

 

2.5" straight to a chrome potato launcher in the rear Kidding but you should get the S-pipe