Upgrading to KO4?
 

I have a b5 s4 and I am having to do a 500 repair on one of my original turbos. (oil leak) I was thinking I should just save up a little and go for the ko4's. what other hardware do I need To get with upgrading to ko4's? Any input will help.

A little info
160k miles
Software upgrade
Recent major tune up (water pump, both belts, coolant/radiator hose)

K04 are pretty much plug and play for your S4. you will probably want to go with new hardware (gaskets, flanges, bolts, etc.) but the actual turbos are a straight up swap.

you are going to need to have your ECU retuned to take advantage of K04 and supporting mods (fueling, intercooler, DPs, etc) would help you get the most out of bigger turbos but they aren't required. every change would also require the ECU to be retuned.

IMO at 160K miles, unless you are planning to dump a whole bunch of money into upgrades, just replace the turbos with K03's

good luck

Thanks for the info. You know a good site to get some ko3's