Which header for Two Brothers Exhaust,

Hey, I bought an '08 WR250R a few weeks ago and it came with a Two Bros slip on. Any idea if there is a header that will work with it? Soloracer.com says the FMF stuff is too big. I noticed on ebay there is a pro circuit header as well as a big gun header. They seem to fit stock exhausts. Think they will work?

Also I bought a P4 powertip to quiet it down a tad. Anyone have a P1 and want to trade?

The Pro circuit on ebay I don't believe is actually for the WRR if you scroll down the ad. The big gun says it will work with the stock muffler so I'd say it would be fine, According to Travis at Thumper Racing, the stock header outperforms the FMF's, it's just not as pretty as stainless