Ive been running a K1 since April time, and im sure my baffles are shot. Ive not taken the bungs out yet, but the noise it makes with them in is incredibly loud. At 2000rpm which is about 60 or 70mph cruising you can feel your brain rattling. When I first fitted it, I used to get headaches, but now its made me a bit deaf so im used to it. It still makes the missus feel sick however. I measured the in cabin noise using an app on my phone (okay, so I doubt if its 100% accurate), and it was coming in at 110db max on my drive home. Bare in mind ive a roadster, so there isnt as much sound proofing with the roof down.
The funniest thing happened this week though. I was driving along and overtook this car. This other car then followed me for about 8->10 miles trying to catch up with me. When we finally stopped at some traffic lights the guy wound his window down and told me my car sounded amazing, best thing he`d ever heard! He`d followed me for all that distance just to tell me!
Im always getting people nearly breaking their neck turning around to see what car im driving when they hear it.