I have an 03 LS650 that I have left pretty much stock.  I have a K&N filter, but have not yet put it on.  I am seriously considering a Super Trapp pipe, simply because it can be  tuned, and seems to have a good rep.

I have two questions really.  First, if I install the K&N and the Super Trapp, how many baffles should I install for good flow, but maintaining the proper back pressure?

Second, if I do the above, I know that I will need to rejet the carb.  What size jets would you recommend.

All advice is greatly appreciated.

You CAN use the Trapp to keep the restriction at stock levels, But WHY?? Spend all that $$ & gain noting? No way.
Jetting is different for each bike it seems, Your location, Feet above sea level, changes the equation,too.
You can use enough baffles to mess things up, but figuring this out is, for me, too tedious, so I slapped it together & Im reasonably happy, If I had the OOOMPH id worry about the last 20% of power I could wring out,.

Now youve handed the smart guys the nfo they need to give you an idea where to start. Good luck & I think thats a great approach

here is my guess.
I would put the eight discs the supertrapp comes with, then do the white spacer mod and up the pilot to whatever Lancer sends ya and go with a 150 main and hold on!
Seviersavage

I ended up going down to 10 discs from 14 but I have a different carb.