Question for Hummer Pro's

[H2Much]

so, I had a little lift done on my ride a while ago. I had 37.5 toyo open country's put on with 20's. I did not want to spend the extra money to have it regeared, so I tried to just roll with it. Obviously, this created a little problem for highway driving, as my ride usually downshifts to push the speed limit and stays in 3rd when highway driving, ony shifting into 4th when it is straight or downhill. I am trying to get it to drive on freeways better without chnging the gearing, so here is my question for everyone:

I have put a chip in it, and this has helped a little, but it is so close to having enough power to get to 4th and just stay there.

Would it help if I was to add an intake and a performance exhaust in this situation? I just need there to be enough power so that my ride can push 4th gear on the highway, but I don't know enough about intakes or exhausts to say that this could give me the little extra I need without having to regear. Please give me some advice if you know about this....

Thanks!