I'm bout to buy my flowmaster 40's but I was wondering if any one will fit? do I need a certain flowmaster? I'm asking because I found a pair on craigslist for $100 and I want to buy them if they'll fit.

 

There is only one style of flowmaster 40's. Take a look on the internet and see what kind of sound you want.

 

no there is not only one style of flowmaster 40's

the 40 series is a good sounding muffler but in order for them to fit on your mustang you need an offset inlet and an offset outlet
you can refer to the force pro thread for more info on this........there is a makeshift picture drawn on there of a muffler

 

Dude, just go with the Flowmaster Force II exhaust system. it has single goes to duals so you have 2 40 series than has the 2 tailpipes.Took me about an hour to put on an i welded my tailpipes to behind the mufflers instead of using those clamps it came with.