It's been about 18 mos for me and they still look brand new, plus my car is parked outside mainly. That said, I only put maybe 2-3k miles on it per year so that helps.
Welp, that's all I got lol. If you had the race MAF then that would've been your problem but since you have the standard bore then you shouldn't have any issues.
The struggle is real. I'm vacationing in Japan and shot the shit with Ryo over at Seeker for a bit and even he said he's not gonna run his FK8 again until winter 🤣
+1 for Mike Sweeney aka MikeTheTuner. He's local to me and dyno tuned me recently but he also specializes in remote tuning. Very satisfied with the results so far.
If you want a PRL-like downpipe wait for the TSP. I spoke with them the other day and they're about 2-3 weeks out.
https://www.twostepperformance.com/products/high-efficiency-downpipe-upgrade-for-2017-2021-honda-civic-type-r-fk8