Engine maintenance before turbo and fueling


Go Kart Newbie
Long story, short, I own a 2018 VW GTI SE DSG since new, have put on a wonderful 101,000 miles. Have always done the required maintenance before time frames, such as DSG fluid, oil, recently had water pump replaced with a carbon cleaning on the valves. Car has an OEM IS38 on EQT custom tune with Autotech HPFP, free flowing intake, downpipe, exhaust, RS7 plugs, RS3 coils, EQT grounding kit, Unitronic intercooler, basically all the bolt on's except charge pipes. With the prices of new cars getting more and more insane and paying $38,000 for a new GTI SE and with my car being paid for a while, I decided to just keep it and go a little further. I'd like to run a higher capacity LPFP as well as an EQT Vortex/XL with upgraded sensors. May also add a bicooler as well as I feel the heat already causes some knock on my tune even with the upgraded stock location intercooler. What would you all recommend I do to make sure I am starting off with a good foundation, engine wise. I notice a little bit of oil on cylinder 4 spark plug when I change them. Car has the infamous rough idle even with the ignition items above. Other than that, the car burns relatively little or no oil, never left me stranded. I'm just yearning for a little more fun but I will not pay for a new car, just a principle thing. So, if you were me and wanted to go the route above, what would you iron out first before making the plunge? This time I plan on having the tune refined while on a dyno than the street since this will be my last and final upgrade. As always, thank-you for your input and take care.