Your power problem isn't going to be helped by installing a crack-prone Banks header and exhaust system, such systems only help a tad at high RPMs. Regearing is what you need to do to get the power back lost from the larger tire size.
Your present gearing is either 3.07 or 3.55. For 35" tires, you want 4.88 gears and for 33" tires, 4.56 is appropriate. The cost of regearing both axles including all parts & labor depends on how well you can dicker/negotiate. Costs start at under $1100 to as high as $1500-1600 depending on the location and your negotiating skills. In other words, never accept the first price they quote you which will usually be much higher than they can actually do the job for.