Hey guys, I just got a '03 Cooper S, my first Mini. I'm considering a smaller s/c pulley but i'm not sure what it can reliably handle as I drive this car daily with the occasional autoX and rallyX. I'm looking at a 17% reduction, do I need higher octane fuel, different plugs, etc...

thanks for the help

 

you should be already running premium in your car ...

A 15% gives approximately 20 horse and no extra mods needed
a 17% should do coil/plugs/ wires/ intake

 

So I don"t need any higher octane then premium at the pump? This is what I should have asked to begin with, I'll try and be more specific. On my subaru rally car when i upped the boost I also went to a colder heat range spark plug, is that something i need to consider for the mini. I've already upgraded coil(msd), plugs(ngk iridium) and cables(nology).

Thanks for the help I really appreciate it

 

17% you should be good to go ...