As far as the gel seat, I can suggest a call to these folks:
They live a few miles from me, are retired from the 9-5, and hit the rally circuit, doing custom gel and foam installations on your seat. Gel doesn't work for me. The solution to the pressure points that "burn my butt" was a wider, firmer seat surface. Be true to your own butt. I have found them to be very reasonably priced for seat work in their own shop. While the gel pads seem to make things worse for me, they are very good with denser foams and are all about helping you get a better seat. When my seat "pleather" gives up the ghost, I'll have them do a rebuild for me.
Exhaust. It is hard for me to wrap my mind around after market exhausts for the KLR 650. The claimed gains are not proving to me to be consistent, and the claimed gains are so marginal, I think it a better investment and appreciable cash outlay to find other performance enhancing improvements for the bike. 3-400 dollar outlay to make a possible 1-3 HP gain on a bike that is as crude and rudimentary as the KLR 650 is like putting headers on your Mom's Buick. Sooner or later, she'll be fed up with the noise, and the upgrade won't help the car's intended purpose. Suspension upgrades may have been a better investment.
While some will boldly and bravely claim that there is a night and day's difference in raw horsepower gains in the after market exhausts, most Dyno testing reveals a 1-2 HP gain, and that usually can't be repeated with Dyno testing consistently. Some tests will show a LOSS of HP. All mechanical theory aside, I suspect the rider that can truly appreciate a 1-2 HP gain on this bike, can ride the same bike with knobby tires over a dime and tell us if it is heads or tails. I have a little over 50,000 miles of my own on one KLR, and I know I'm not that rider.