Irrespective of Other people claim of the 20HP or maybe more improve- on modified heads by yourself, this is just unattainable devoid of camshaft or pistons modified. Toyota has casted and machined all their 4 valve heads to pretty shut and correct tolerances for Road (and rally) use. just lately https://franciscozlqfq.blogrelation.com/32680643/5-simple-techniques-for-4age-engine-sale