hey skyline350gt-

im liking my 421b so far (even more than my old P5's) and have about 15 tanks through it. from tank 8 to about tank 10 the motor kept richening itself. did you have this problem too? it stopped after the races really got going and ran steady for the day (250-270F) but im wondering how much cooler it will run after the full break-in.
oh- and what size carb restrictor are you using and why?


henderson- any top-end pipe will work good with that motor. after about 1.5-2 gallons of fuel your bottom end should really wake up and you will have no need for the waller adapter. 9886/086 pipes are good and so is the O.S. 2050. i just got a Jammin JP-1 pipe and love it on my 421b which has similar characteristics of the P5. i think its a low/mid range pipe but it seems to work very good with the top side as well.