SLP v. Flowmasters

Well let me be the first one to tell ya because I know someone is going to tell you....go to mustangexhaust.com

Power wise isn't going to be that much or that much difference. Although someone said that just by going to a SLP Catback they gained about 18hp...How true it is I don't know.
But depending on what type of sound you like. The Flows will give you more of a rumbly muscle car sound, while the SLP will give you more of a loud raspy type of Nascar or exotic car type sound. But it also depends on what kind of midpipe you are going to run be it X or H pipe.

Go with the Mac Catback...., even though I have Flows on mine....
Since you don't want to spend the money to get the Bassanis, I know the Borlas are out of the question.

P.S. Get the Midpipe and the Catback installed at the same time. You'll feel the power difference better than if you got them installed separately.
And decide now if you are going to keep the factory headers or go with Longtubes. That'll dictate what midpipe you need to get now.....

I have loudmouth I's and I love them. From what i hear they are suppose to be the most free flowing mufflers out there. Being true i dont know. If you want loud go slp.