RE: Art-Tech Shark 450
that's the motor that I put in Nitro's Shark and with the stock pinion the head speed is quite high. If you use that motor I'd use a rex 450 11 or 12 tooth pinion, that should give you the same head speed as stock. I'd start with the 11 and if you find the head a little slow up to the 12 but my calculations show the 11 should be right on the money.