i have a aristo swap in my sc300, i was doing a top speed run and i swear i hit a speed cut at 120 or so mph, i completly lost power for a sec then it came back then i sped up again then it cut me off again, i have a FCD installed. im on a 5speed. is there some sort of speed cut going on here?

 

Yes. There i a speed governer on the JDM ECU's.

Also, there's a thread about this about three posts down....Its called a speed limit defencer.