Welcome to JeepLab. Seems that there is finally someone other than myself who has the 3.8. I run 35's with a 2.5" lift and I use a Flashpaq Tuner. This is my daily driver but it also sees the earth in its natural habitat on occasion.

The Flashpaq will help out some but it's no substitute for regearing. I didn't buy a Jeep to go fast. I would be happy with just not loosing power on hills. The Flashpaq still doesn't overcome that. It's a relative minor solution for a bigger issue.

The exhaust is only going to let out what the engine is taking in. Aftermarket exhaust will be more streamlined and let out the exhaust more efficiently while maintaining proper back-pressure.

Just remember, no matter which route you take, you are driving a billboard.