I would read up a bit on the bike before you start doing modifications.

Jesse at Kientech is a good source for DR stuff and has some gooe items for sale and knowledge about jetting and re-springing the bike.

Verle Nelson has owned many bikes, lots of KLR's and DR's. Has done lots of miles on them and has some good set up ideas too. Really knows his stuff, IMO. His page is loaded with very specific info on using various items on the DR. Excellent page.

KienTech Engineering

Suzuki DR650

You can read back through this thread to see some of the things I've done. One thing I intend to buy for my bike is a fork brace. Doesn't need it much when unloaded but needs it when loaded up with gear.

The bike is so simple to work on, you will find it a pleasure to own. Mine has performed well on several long dual sport rides, but in Mexico was not so great
in the dirt due to me overloading the bike. I was carrying 100 lbs (45 kgs) in GIVI hard bags on board plus with 5 gallons of fuel in the IMS tank. Not good. Important to balance suspension when carrying a load to maintain good front to rear balance.

You should plan to play around with the bike a bit. Go ride a NEW stock bike to gain perspective and a baseline for adjustments. IMO, re-jetting is essential. The Dyno-jet kit will not only add power everywhere, it also will still get good fuel economy if set up correctly and the motor will run cooler. It's the needle that makes the difference....it's all in the needle. Took me a while to figure this one out. So open up that airbox and re-jet. The only trade off is you'll have to clean your air filter more often .....or use Filter Skins!

The bike seems to work well with a variety of tires but the stock Trail Wings work really well. The rear T-Wing wears out to quickly but the front tire works well, is very cheap and lastl 10,000 miles.

For long road trips try a Avon Distanzia for a rear tire. I'm using Pirelli Scopions AT's for day to day riding. Any front will be OK on a long ride.

2003 model may have a leaky base gasket. Seal it with silicone. Should hold it.
Staintunes are wonderful but very very pricey....and I seriously doubt it will add much power....if any. My FMF Q2 did not.....but saved 4 kgs. of weight. I sold it.....too loud.

I had hard GIVI luggage on for Mexico and this is where I ran into probs. I've now gone back to soft bags and am down to just 60 lbs. fully loaded for the long haul. Bike handling is night and day better. I have heavy springs, fork brace coming soon. The GIVI bags empty and their racks weighed 26 lbs. So that is a lot of weight for convenience and ruined the handling on the DR.

Good luck.

__________________
Patrick passed Dec 2018. RIP Patrick!