NAVYMAN

If you have the money for the long tubes then I would say go for it. with as far as you drive I would stay with what ever gears you have for now and spend that money else where.

clowe1965

You listed a tune as a possibility so I assumed. Do you have a tune with it or just the SCT tuner? If you just have the tuner you still need a tune to adjust the O2 sensors for long tubes.

Stick with the 3.55 gears. If you get 3.73s or 4.10s and ever go with a supercharger you will have serious issues with traction without drag radials or slicks. If you want to change that later then go for the 3.73s, I haven't heard anyone say they wanted to take them back off on a n/a car.

Cats or off road set ups depend on what you want and where you live. Lost of states require inspections, but IIRC Oklahoma does not so you can go with either. I left mine in because of noise reasons and speculation of losing low end torque. Admittedly the hi-flow cats that most kits come with are no where near the factory systems in terms of sound deadening capability and flow restrictions.

You gain more at the top end with an off road setup, but a minor loss of low end torque. I haven't seen a comparison of an off road setup vs a catted setup with hi flow cats. The typical gain range is 10-20 hp from stock to an o/r x.

Sorry for the lengthy explanation, I'm certain you knew some of it already.

Have you given any thought into suspension?

scottmach

To turn off the rear o2's yes otherwise there's no other changes needed with longtubes.

UPRSharad

Here is a great choice in exhaust:

http://www.uprproducts.com/american-...134-gt-11.html

Or you could go for some suspension upgrades.

http://www.uprproducts.com/05-09-mus...uspension.html

AMDanBailer

It sounds like you already have the tune on the way so that's a great start! On my 2011 GT I went with Long Tubes, Catted X and 3.73 gears. I definitely recommend doing all of these mods, it was night and day difference over the stock set up!

If you're looking for more rumble out of your 5.0L than go with the Long Tubes first! However the gears are one of the most beneficial mods when it comes to the butt dyno.

I hope this helps! Let me know if you have any questions or need some assistance in the future.

-Dan

CrzyHrs

I've got 3.73's and I daily drive 50 miles back and forth to work, thats what 6th gear is for. I wish my 5.0 came with lower gears just so I could tell the difference in swapping to the 3.73's. I love them, when I run at the drag strip I cross the line topping out fourth gear so I don't have an extra shift. Since I don't plan on going FI anytime soon I'm not worrying about changing the gears out. Also, think about a short throw shifter. That's going to be my next mod.