lads i'm after buying a race zapcat with a 40hp yam/mariner twin on it, 6E9 or 40EM i remember that yamaha used to make a 55hp twin back in the day. i've had a look round here and google land but can't seem to find any info un upgrading or is it possible. i know a few will say change the engine but i'm unemployed and broke after buying it please help me as i want to beat my friends with their 50hp tohatsus i'm wonedering is it just a jet and exhaust plate or timing? thanks (oh the hull is rated for 70hp so is well able for mine)