What should my next mod be?

[Rshgt2]

It's time for my new mod, and I need help from you guys. Here's my question: Which of the followings would make the most noticable difference -3:73 gears w/ diablo chip, X-pipe w/ cats, and 70mm throttle body and headers combo?

If you can, please also let me know how each mod affect fuel economy. Thanks.

[Roush 5.0]

You'll see a major difference if you got the X-pipe with no cats and the headers at the same time. And maybe if you get the chip and gears you might feel a difference, it's not a major notice but it's also a waste at this time. And as for fuel wise, forget it you have a V8 it should be sucking gas and hauling ass.

[fast94five-oh]

well im sure the last thing you want is advice from me, but I do work on mustangs for a living. The mustang headers are great, if you own a 5.0. The 4.6 headers are slightly more restrictive. On my car I put on BBK equal length shortys, and an x-pipe without cats. Sounds like a full out race car with my SVO exhaust. The low end torque is very noticable. I can now whip a trans-am, something I wasn't able to do before this mod. As for the hp, you will notice a difference but not much. The headers are a pain in the ass to install, and you must get the x-pipe welded when you get it installed. Also know that it hangs below the trans, not on either side of it like the stock exhaust. You wont just catch a little rubber in second, with this mod you will full out turn over the tires over pretty well. If you buy the headers, from any manufacturer, you must first grind down the welds on the inside of the engine side of the header tube.

[Rshgt2]

sounds like an x-pipe is the way to go. I would go with the one w/ cats though.....keeping it clean.