146mph?! I would take that tune out and check your sprockets. Maybe he put on bigger rear, smaller front for more wheelie power. That bike should definitely hit 180-200mph indicated with no problems. I fought a similar issue with my ZX12R, was limiting itself to 7k rpm when it should go up to 11.5k, so only hitting 130mph instead of 190+. I replaced the fuel pump and filter, spark plugs, air filters, pulled out the power commander it came with cause it probably had a shitty tune, and was finally able to go 190+. Good luck with everything.