After purchase I ran the car for several weeks and she was running spot on, beautiful. Then I upgraded the throttle body to 52 mm and fitted a cold air feed enclosed induction kit. I noticed an excellent improvement in the car. Then I fitted the manifold and TT MK7 back box. A subtle difference was noticed with these additions, she had more torque and revved much more freely....At this point she was running perfect and I was used to the mods....Then after about a month (driven daily) the cat started to rattle but there was NO drop off in performance whatsoever. Then on a country road blast she suddenly started choking up at about 4500 rpm...Literally just like that, one second revving as free as a bird then bang...Choked. I took her straight home at low speed. Replaced the cat with the decat pipe and as soon as I took her out I noticed a considerable difference...Not a slight imagined dream...A very real difference, so I ran my usual tests, hit the rev limiter in every gear and sure enough, about 5mph more in every gear....I don't need to convince myself or anyone else. Replacing the cat with a pipe was the best mod I have done to Molly, period.