It looks like 18 of the 20hp gain are in the injectors,and the gains are given back during the shift on the 01's. I have a 2000,my dad has a 2001,both are auto's both had 4. 10'. The 01 felt noticeeably quicker,and stronger,the difference is easy to feel. A set of injectors will even them right out,since 275's give 33hp on an 01,and 50 hp on a 2000.