I paid $160 for my 2 1/4 catback... got a fair bit of low end out of it... lost a little up around 6000Rpm but yeah low end is awseme. I use it more than top end so it was a great move

Before my car used to lag up until 3000 now it kicks around 2400-2500 mark.

It will pull from 1500RPM to 3000 fairly quickly... in 5th gear. I very rarly change out of 5th ever since i had it installed.

Thats why i'd go 2 1/4. If you want more top end back get 4-2-1 extractors.