vcyclenut sells a setup with full exhaust working with an OEM ZX10R header, with a new mid and can. Get it with the sprint filter and flash. This is the setup I'm running.
The challenge with a Guhl flash is they, and many others only go for tuning for wide open throttle. Guys like vcyclenut and Ivan's go after a tune on the dyno, then datalog the bike to fix real world issues like mid throttle, on-off throttle hesitation, etc. Ivan doesn't make an H2 SX tune unfortunately, and vcyclenut does a great job fortunately. I've bought from both of them for a few bikes and am quite pleased.