There are lots of other option out now, for reliability and a good, strong, and mostly very fun power band, BW K04s are great. They fit properly, there is lots of OTS tuning already available, and on a stock motor, the difference between a K04 and a FT or even RS6 turbo is going to be marginal. Sure, you can push those bigger turbos harder but then you start sacrificing reliability and potentially your rods down the road. K04s still make solid power and are still a viable contender even when compared to some of the bigger options out there.
I am about to yank my motor out of my black s4 which has blown K04s at the moment. I've been in a similar debate, do I just rebuild the K04s, make it easy, and go have fun, or do I go the extra mile and drop some rods in the motor and get some F21's or BW RS6's and push them harder......
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