Any luck adding HP to newer Suburban/Yukon for tow

I have a 2003 Suburban to tow my MB B52. It tows ok, but seems just a little underpowered. I was going to step up to a 07 or 08 Suburban 6.0 1/2 ton or go with a 3/4 ton 6.0 to get a little more pull power.

Stock HP on the regular 5.3 is 320 (35 HP more than my 03).

Has anyone used any bolt on HP adds or a chip to boost HP? Does it make much difference?

There is a lot more selection in 5.3 Suburbans than 6.0. I have looked at Denali and Escalade, but rather stick with Chevy if possible.

Thanks for any input.