S4Phantom

My 2000 S4 is stock, except for Bilstein coilovers and RS4 bumper w/halogens. It seems the ko4 upgrade is popular. What is needed for the upgrade besides turbos/intercoolers? Do I need another ECU/Reprogramming? Cams, Intake manifold, etc...? I see they have forged rods you can drop right in. Anyone who has the upgrade please comment on your likes and dislikes on the modification!!

Flyboy

Are you asking for impressions on K04's? There's a ton of posts on this forum over the past decade that they've been available on the S4.

The absolute minimum would be the turbo's, a silicone reducer to make the transition from a chopped off K03 inlet to the K04 compressor inlet, and an MBC to keep boost within the stock injector capabilities.

Most of the aftermarket parts you mention won't do much for a K04 car.

S4Phantom

Will the stock S4 intercoolers be sufficient for the K04's?

shawnoc2003

You need to do a bit more searching on the forums.

Anytime you want to go with larger turbo's you're going to need the ECU reprogrammed. You will also want larger intecoolers and will need larger injectors (or more of them). The hoses need changed and you'll want to upgrade the exhaust as well.

Stay under 22lbs of boost and you shouldn't have to open up the motor.

Be ready to spend anywhere from %5 to %15k depending on how fast you want to go.

Flyboy

Depends on what you mean by sufficient. Nothing bad is going to happen if you use stock IC's with K04's, but aftermarket IC's are a popular upgrade since they aren't as restrictive and cool better. You wouldn't have to upgrade IC's, but would probably want to eventually.