Irrespective of Other individuals assert of a 20HP or even more improve- on modified heads by yourself, this is simply difficult without having camshaft or pistons improved. Toyota has casted and machined all their 4 valve heads to incredibly close and correct tolerances for Avenue (and rally) use. This engine https://4a-geengineforsale41098.bluxeblog.com/58709517/rumored-buzz-on-4age-20v-turbo-engine-for-sale