Here is a quick comparison of all 3 for you guys explaining advantages and disadvantages of each type. (R53 Cooper S)
STD CRANK PULLEY. These are a very heavy but damped item . Earlier versions weighed 7 pounds ! Later versions 5.5 pounds. They can suffer with age causing a cha cha cha sound under load. Also concentricity can be an issue increasing the risk of dropping a belt . The later version is better, partly as …is lighter but usually of lower mileage to.
ATI Pulley…..This is an aftermarket item that is actually marginally heavier than std ( 5.8 pounds), and quite expensive. Apart from that if your stock pulley has had it and you are adamant you want to run above the stock 7000 rev limit via remap it could be a good option.
GTT Crank Pulley V2…These are a 2 part item with steel centre sleeve on the nose of the crank, with a slide on & bolt on hard anodised 6 spoke alloy wheel . Latest versions also include a ‘belt & braces approach’ by bonding damping patches to the inside of all 6 spokes . Advantages are :-
1) VERY light , at approx. 1 pound weight the STD and ATI items are nearly 6 times heavier!
2) Perfect balance + perfect concentricity even under heavy load.
3) Best possible engine spool up /throttle response time.
4) Hard anodised so will not corrode or wear in the way mild steel or bare alloy will.
5) Good Value ….at around half the price of ATI item for example.
6) Proven over 12 year period, having covered very high mileages and used regularly on track to.
7) Steel sleeve allows correct interference fit to the steel crankshaft yet can be removed without damage in the way an interference fit ‘all alloy’ pulley can.
8) Available in 5 sizes to fine tune boost (0% 1% 2% 3% 4%).
Disadvantages…Only designed for stock rev limit of 7000rpm , as a supercharged car this as high as we recommend anyway irrespective of crank pulley choice for various other reasons. Beware ignorant tuners who ignore instructions, increase rev limit then try and blame the pulley when a 12 year old oil pump fails ! Website clearly explains this to. This is true of all this type of pulley BTW. Other companies don’t even mention the max rev limit with their pulley…..They should do IMO .
So in summary with stock 7000 rev limit GTT Crank Pulley ticks all the boxes. With increased limit use a good (later version) STD item or if passed its best then maybe the ATI item.