Which turbos should i replace my poor ko3's with? I was looking at ko4's but not sure thats what i wanted. I really dont want anything that wont bolt up to the manifolds, i was considering the atp gt2x but dont know much about it... then i was also considering other ko4's with a different compressor and or turbine. Also was considering spool time, bigger turbos make more boost yes but take longer to spool, both would be great, something that can spool up fast but hold 25-30psi to red line and still be in the turbochargers efficiency range. Anyone got any ideas?

Hahn/Mitsubishi Super16G, quick spool, capable of 30psi, I don't think I've seen one fail, only issue would be that they won't bolt up to your manifolds, they have a T3 flange.......great turbos.

if this is your question, then k04's are for you..

a custom or dual big turbo setup on the S4 is obviously more than you will be able to handle..

there is nothing wrong with 400+Awhp/Awtq. k04's are an amazing little pair. not too many cars you'll find on the street will be able to keep up with you..

oh, and BTW, ATP does not offer any turbo for the 2.7t motor. at least nothing short of 100% custom.. the 2.7t eliminator turbo project was called off and closed down..

but if you really want some info, look into VAG motorsport. Vast Performance,and Auto Speed Performance. they all build BT S4's

Yea, it's a great turbo, but WAY to big for the S4! K04's are so much smaller.

Honestly, if you want something that is simple & reliable, plus supported, you got to stick to K04's, it's also the cheapest option out there.