Best Bang for Buck Parts

Hello, New guy here. I don't own a new mustang, but my real good buddy just bought an '07 GT Automatic.

It's not gonna take long for him to start throwing parts at it. He doesnt use the internet much, so I figure I'll ask questions for him.

I get MM&F every month. I have a high 13 sec f150 NA... so I'm not a complete modification idiot. I see all kinds of parts in there. I just want some first hand experience from some of you guys.

I know he is gonna want some kind of exhaust first. If I'm not mistaking, the GT's already have a built in "H-pipe"... Is this true?

I have an X-Pipe here already to weld in.. that's taken care of. Just changing mufflers will net only a minimal HP/TQ gain, so we don't expect an HP gain there... He wants a good sound without being too loud..

I know flowmasters sound pretty good, but the price for the flowmaster kit is a little high every that I've seen advertised.

Anyways.. best bang for the buck mods.

I'd imaging a tuner would be the best thing because he can riase shift points and firmness. I'm gonna go ahead and say that's the #1 mod.

Custom tune is always better than canned, so who's my options? Who's the best?

Intake? I know they only provide about 10HP if your lucky, but they sound good under WOT. What's the best out there?

Any opinions and help are much appreciated.

I'm gonna continue to comb through these forums to try to answer some of my other questions.

Thanks:SNSign:

He plans on adding some 4.10s.... I tried talking him into 4.30's but with an auto.. Might be a little steep.

Thanks guys... He already ordered flowmasters, bolt-on mufflers.