Irrespective of others declare of a 20HP or more enhance- on modified heads by itself, this is actually unattainable devoid of camshaft or pistons improved. Toyota has casted and machined all their 4 valve heads to extremely close and exact tolerances for street (and rally) use. Conclusion The 4Age 20V https://4age-20v-blacktop-for-sal60360.blogunteer.com/26392387/the-best-side-of-blacktop-4age