Like I said, can't say it was completely safe, lol. At the time I didn't have a scanner to read KR or a tuner. It did run good, I messed with a Mercedes SL55 once. Could keep with him multiple times up to 135 or more, but couldn't pass him. Don't think I want to go that fast again. When I'm done my build, I'll have to see about KR cause I plan on using that M90 before building the M112. I'll have a few more flow mods than then so should see lower PSI. Still torn on NA or SC piston. Have to take some measurements of the rods and pistons when I get a chance.