I have an '04 B6 A4 1.8T Quattro/Tip that I have been working on here and there. The car has had the timing chain service done around 30k miles ago. The car currently has a Forge 007 diverter, new GKN Loebro front axles, new SKF front wheel bearings, new front/rear differential fluid, trans fluid, filter and gasket, larger B7 calipers with Brembo 320mm x 30mm front rotors and ceramic pads.

The car runs and drives pretty great. I purchased Motoza's Stage 1 tune but I'm trying to get everything ready to start sending them my logs for them to write the tune. I'm also collecting some parts to swap out the exhaust to a 3" test pipe to 2.5" duals, FMIC and replace the turbo.

Been trying to figure out the best way to go about upgrading the turbo. I was planning on trying to rebuild a good K04 using the larger 51mm inducer, 38mm exducer and 4.4mm tip height from my K03S the car came with. But I don't know if there are really any good rebuild parts out there for the K04? The reason I'm considering this option is because I have a good condition K04 and better flowing manifold on hand and the car currently has the stock K03S to snag the larger compressor wheel and housing from. Then rebuild it while I'm at it.

Otherwise I'll be moving up to a T3 or a GT28R which means a new manifold unless I come across one of the elim versions, plus any other changes that go with changing the turbo size/location that much. I thought if I go this route I may as well go all in and look at upgrading the rods, crank, manual swap, etc. I'm only wanting to try to hit 250HP at the wheels and thought a well built K04 with the tune, <550cc injectors, FMIC, 3" MAF and exhaust will get me close on 93 pump gas and not be touchy to drive.

I really enjoy driving the car, it gets pretty decent mileage, it's AWD and I swapped in a S4/Tip steering wheel with paddles which makes the Tip fun to drive anyway. I'm just curious if there are any sources for high quality K04 rebuild parts or any upgrades like swapping the K03S compressor assy onto the K04 that can help me squeeze all I can without moving into the bigger turbos/manifolds?

Gratuitous pic, still waiting on my Ultrasport fog grills so I just popped the base fog grills in the openings as placeholders:

The wheels are 16x8 et35 56.1 from a '00-'02 A6 Allroad if I remember correctly? The car definitely sits better on the 35mm offset. Still haven't found the right set of 18's for it so these are better than the factory 43mm offset 16x7s. They'll be great winter wheels eventually.
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