The_Shirt

What is the difference between the 2.5" and 3" Magnaflow Performance cat-back systems? I am getting ready to put one or the other on my 06 GT 4.6L, and am curious on the difference. Is it an actual performance difference or an aesthetics issue? They have the dyna-tune results on their site, but they aren't both on the same car (one is on a GT 4.6L, other on a GT500). Thanks in advance for any insight...bill

tonkpils555666sas

I wouldnt assume there is much of a performance difference at all. Generally, most catbacks see similar results. Variation in brand is more variation in sound/looks... 3" would probably be louder... but not by much... The tips would look good though.

heres the link to my exhaust with the 2.5... but i also have lt headers and no cats on the x pipe. The system is generally softer than others but when you get on it, they sound loud and fun... http://www.youtube.com/watch?v=Eo7SXio2Qf8

Blacksmoke

2.5 is plenty, you dont need 3. In fact you will probablly loose some ummph with 3 unless you have a GT500 or something.
Definatly stay with 2.5.

And no 3 won't give you a noticable difference in sound.

2k6silvergt

There will be a slight sound difference but nothing that noticeable. And there really isn't going to be a power difference unless you are making a lot of horsepower.

kiki07gt

I put the 3.5" Ford Racing axle back and got roughly a 12-15hp increase in my GT. The sound is absolutely incredible and the look with the rolled stainless tips from the back is very stout and beefy! I do find some drone in the car about 1800rmp which goes away over 2000rpm.

http://www.fordracingparts.com/parts...tKeyField=7707

However - they are not legal for sound in CA. Good luck to you!

blackS197

If you plan on going FI or already FI I would get the 3 inch. I have the 2 1/2 magnapaks and would of go the 3 if it were out back then.

howarmat

The dyno you were using was wrong. Axlebacks just dont give any gains for our cars. It would be nice to see gains like that though

The_Shirt

Thanks all! The 2.5's are bought, paid for, and will be installed Tuesday. In reference to BlackS197, what is FI? I thought fuel-injected, but haven't most cars been fuel injected for a long time now?

modaddict

'Forced Induction', i.e. supercharger, turbo, Nitrous, etc.

The_Shirt

Thanks once again. Nope, no plans here to make that heavy of a modification...