MaXXing Performance

I use my jeep for deliveries and was wondering how to get more power from that huge 4.0L.

I'm sure there must be stuff out there for these motors.

So far, I have:
1. Dual exhaust system inc aftermarket CAT
2. 2 BMW intakes (lots of modds) to make a good CAI

All sounds great and engine revs better and yes, there is a gain, but can I go any further without forced induction??