Answer:
how you modify a crf150f firs what do you want to modify it for if it is for racing than allot has to be done first you goin to want to jet it and then replace the fork springs and rear shock and then your goin to want to get a good exhaust system and then your goin to want to get octaine booster and a new air filter
if you wat mody it for trail than nothing it is a pre built trail boss