Don't. Just get it done. Had mine done this morning after watching videos and thinking it sounded very tinny. Was very apprehensive about getting it done, worried about flatspots, it sounding crap. Well it doesn't, and I'm quite surprised. I was booked in this morning and considered not going but just went for it. It doesn't sound half as tinny as it does on the videos on YouTube and the pop on every gearchange is brilliant. The flatspot is noticeable, but I tend to sit in 3rd gear at 30mph so I've only noticed it once so far, and it really didn't bother me. So for £66, or whatever it will cost you, get it done. Great cheap mod and I'm pleasantly surprised. Even my missus said it sounds ok and she hated my Mountuned Fiesta that popped like a machine gun!