The 5858 is larger than the Vargas but has a lower power output than the 5862, but it has a better spool than the 5862 witch sits around 4k where the 5858 will be somewhere between 3500 and 3750RPMs which is more usable. It will have more lag than the Vargas but should have a higher max output. The max for the 5862 is around 560HP I think the 5858 is somewhere north of 500 like 520 or so. The Vargas S2 is near the same output as the 5858 but a hair lower. Would have to compare the inducer/exducer sizes. The Turbonetics is a hair smaller as you stated but should make better power overall being a ball bearing unit, should spool a hint faster and being somewhere in between the Stock but much larger and the Vargas makes it a better option as it also has a similar power output rating (round 520HP) in a small package. As always though you will not get there on the stock fuel setup.