so awesome man! what events are you joining at Sonoma? would love to join you at one, maybe laguna also.
Next time you're at Sonoma you should really drive up the hill and check out the shifter karts track also if you haven't before. They are the motorsports equivalent of crystal meth, but in a good way.
i have ~450whp GTI with stoptech brakes and soon to have EQT coilovers too, I would be thrilled to break the 2 min mark at Sonoma on Mp4s michelin tires but I just like having fun and am not that serious.
one thing i would strongly recommend thinking about is getting an EQT tune on E30 or E50 fuel mix. The stock mk7 fuel system will easily support that on an is20 turbo (my car made 460whp on stock fuel system with E48 fuel and is38x turbo on Ed's EQT dyno), the improved torque and throttle response is profound (my car picked up >65whp and 65 wheel torque from 91 to E50) but even better my car runs a touch cooler and I think the improved octane and cooling of ethanol fuel really helps the reliability of these Mk7 engines. My car has been 460+whp now for like 35k miles without any issues which I attribute mostly to the E50 fuel mix I run 100% of the time. I believe the reason so many people fry the rings or break ring lands especially in cylinder 4 in these motors I believe is because these cars run reallllly hot EGTs on pump gas when they are turned up, and the ethanol makes a massive improvement in this regard. Your car will be faster, less susceptible to heat soak, and imo will be also far more reliable over time, and you can also sell the COBB later whenever you sell your car and recoup a lot of your money and the Jb4 is easy to sell also.
my EQT DSG tune absolutely transformed my car also and is amazing. hard to explain how much better the car is with EQT DSG tune, I would not have believe it previously. You're welcome to drive my car sometime if you want to see what you think.
I would also say that my car with is38x turbo, MAperformance catted/resonated downpipe, and stock muffler is perfect balance of roudy when on the throttle but quiet when getting groceries or hauling kids around and nearly zero drone.
If I was to do the turbo again I would just get the base EQT vortex turbo and not an is38 or is38x, the spool on E3o or E50 fuel is basically the same as an is38 and I believe they are more reliable with less backpressure so the motor will last longer and that ~400-420whp level on ethanol blend fuel on these cars is the true sweetspot, which an EQT vortex turbo can do forever with great response. Plus you can turn it up later on if you ever want to, but honestly my car at 460whp on EQT dyno (which reads high so let's call it 415whp on a normal dyno?) just cracks me up everytime I drive it and the car was super reliable and also quiet like stock.