I'm looking to upgrade a stock EVO. The bike is a 97 Heritage Classic. I basically want more HP & TQ. I'm just not sure where to start.....Any ideas?

 

Your sig says you've also got a NightTrain with some mods. The TC and the Evo are similar in the way they respond to modifications. Do you want the Evo to perform differently than the TC? If you just want a little more poop, go with the better air cleaner, freer exhaust and re-jetted carb. I always believe in a cam change in order to rid the bike of the stock oddball EPA timing, although the Evo cams weren't near as bad as the current ones. My own bike, with an Andrews EV13 cam, doesn't feel that different from stock unless you whack the throttle, or get in a low traction situation (like sand left over from winter at intersections). If you really want to get racy you need a cam with more duration. On an Evo, change the lifters and use the common Torrington replacement inner cam bearing. Those are known weak points. I use Crane lifters in mine. But I assume some of this stuff has been done already to a ten year old bike.
I wouldn't recommend the Thunderheader for any bike. It's OK for racing, but there are better performing pipes out there. Simply changing the mufflers works fine for all but the raciest bikes.

 

Free flowing exhaust (doesn't need to be loud and obnoxious)-use SuperTrapp slipons with 18discs on my FLHS
Free breathing air cleaner, SE or aftermarket-got the SE on mine
Better cam, Andrews EV27 is a nice cam for a heavy bike-got it on mine
SE or aftermarket ignition to get a higher rev limit-got a Dyna on mine
Rejet and dyno tune the CV carb

I've done all that to mine andI'm at 70hp/80tq.

Want some more:
Raise the compression to 9.5:1
Have the stock heads street ported

This should jump the numbers to somewhere around 80hp/90tq and still be able to run pump premium fuel without an appreciable decrease in engine life.

 

Just got through with my 97 Heritage Classic. 80.5 HP and 89 ft lb
K&N breather and filter
SE coil
SE ignition
Stock header pipes with SE balony cut slip on's
Heads ported and Polished by Hildreth Performance in Alabama
Andrews EV27 Cam
Dyno Jet Kit on stock CV Carb and Dyno tuned by TNT Dyno performance in Nashville
Real Happy

 

That depends on your budget. A/C, exhaust and cam are the standard mods.
I like the looks of BigHearn's setup, that's alot of TQ for an 80" motor.

My Evo was showing some age so Iupgraded with a new 05

 

S&S E carb
Andrews EV27
Crane ignition

will let you know when it's up. Hope that's soon, too!