99 SE,
You should be able to gain an additional 10 HP relatively easily if you are willing to do the work yourself. Excluding the UIM/LIM, you could optimize your TB and a better air cleaner set up, gut the precats, and remove the resonator and should net you an easy 10 hp. You should be able to do those 3 things for under $100 bucks if you do it yourself. The biggest cost would be the intake.
