Inspite of others declare of a 20HP or even more maximize- on modified heads by yourself, this is simply unattainable without having camshaft or pistons improved. Toyota has casted and machined all their 4 valve heads to really near and precise tolerances for street (and rally) use. If offered more https://4age-20v-blacktop-for-sal27047.uzblog.net/a-review-of-4age-20v-itb-40995670