what jets do i use?

[ridesaredklr]

My 650 (2004 KLR) got a Supertrapp IDS2 and lost power in the higher rpm range. The pipe has all but one disc in it. I got the Supertrapp from ebay and completely rebuilt it/repacked the fiberglass, cleaned it, sanded and polished the shell till it looks like chrome. It came out beautiful and sounds awsome. My guess is it needs jetting; the dealer says might need to open the airbox some (I dont know what that means), the websites (forget which) claim I need the K&N Filter and open the airbox...I just want my bike to run well. The dealer looked up the stock jet and if I recall it is a 148 main-jet. Please help me out. I want to keep costs down. My elevation is 7500 above sea level if that helps. I have not looked at the plug yet. can anyone help me?

[Gravy Dave]

i am guessing that by opening the air box they mean drilling holes in the lid or removing it