engineer certificates

[MonsterBusa]

Yeah, an aftermarket turbo isn't legal anymore (since emission control come in). Main issues are noise, brakes and emissions. You could get it to pass noise and brakes with some playing around, but emissions would get you. Some nasties in the exhaust go sky high with hotter combustion. Testing would be rediculously expensive even if you could get the bike to pass (tens of thousands).

I haven't tried insurance, but I expect most of them will have the old legal clause where any illegal mods are not covered. And it's in most state's reg guidelines these days that affecting ADRs without an engineers report is illegal.