Stock H Pipe????
 

What is up with four cats on my 04 GT. Do these cars have to have a lot of backpressure or what, I have never seen a car with four cats unless its in Cali. Im thinking about getting rid of the stock H pipe from the manifolds to the mufflers and replace it with a offroad X pipe and 2 chamber flows. Any opinions.

Justa a thought, as you used to drive a camaro, SLP makes an awesome exhaust now for the mustang called the SLP Loudmouth. A Cat back system is less than $350 and they have headers too as well as X pipes.

Going with an off-road X pipe and two chamber flows is a great option.

Check out www.mustangexhaust.com as they have hundreds of sound clips for all sorts of mustang exhausts that you can download.

Some 99+ Cali stangs have 6 cats (2 pre-heater and 4 cats).

I know mustangs had 4 cats in 86, I think they were on there even before then.

I have a Mac Cat H with 2 high flow cats that is supposed to pass emmissions (haven't tried yet, will know for sure in June), but it kept kicking the check engine soon light on, so I had to put mils eliminators on it to stop that. 99 GT.:D

Thanks for all the advise, I'm probably gonna go with the offroad pipe x pipe and 2 chamber flows, that should get out all the forced air in a quick enough fasion. I will definately check on the SLP stuff before I make my final decision. I can't wait to see what a difference its gonna make getting rid of all that restriction.

You are aware of course that flowmasters don't even flow as well as your stock mufflers? Dynomax, Magnaflows, Macs, almost any of them flow better than flowmaster.

I 2nd
blowmasters are just for sound no real power in them

Yeah i had heard that somewhere. Any opinions on Hooker mufflers? Or better yet my second choice is Borla, Im sure those will do great, what do yall think? Kinda sucks that such a good sounding muffler doesn't flow worth a damn.

Nothing wrong with Borla, if you can afford them, by all means, I had some used ones on the V6 vert I used to have, loved them!:D