nissan produced the l20b engine in a mass production and in doing so not any 2 of the same engine was a match for parts each had its own slightly different changes although the l20b engines wer a great engine for getting alot of power out of take for example a set of twin carburettors and a head off an l18 engine throw in an aftermarket cam and a set of exstractors and you are easilly makeing and extra 50-100 hp out of the engine that doesnt mean to say that nitros and a methanol mix cant be adapted for the hard core enthusiest an overbore bigger pistons race crank and cam with the engine and a holly 850 carb and you have one of the most lethal l20b engines in the work ive run mine with all different combinations and my fastest 1/4mile run was a very impressive 10.25 @265kph this was not expected to happen at all because i was experimenting with a new type of design to the pistons,head,cam and crank so if you really wish to modify an l20b engine it is a good thing to not go to a car parts dealer but it is good to go to the local race track and ask some of the racers because 9 times out of 10 they have either had one or know what to do