I did it a couple of months ago. I was expecting a lot. Nope. Almost the same. But when I came back to the workshop to pick up the car mechanic asked me why didn't I put an exhaust flap before the rear silencer. And there it was standing on his table, for only 140 euros, mounting included. Couldn't resist. 15 minutes later I had it installed. Now, that made a huge difference. I push a button to open it and car gets into MONSTER mode. Pops, bangs, farts and stuff. Almost straight pipe (it still has a GPF). If you are going to spend 200+ pounds on just a res delete sincerely its not worth it. It does sound a bit better but thats probably not what you are looking for. It is really hard to record how much louder it sounds with an iphone but I promise I will use my professional sound recorder and post the sound here just so you can have a picture of difference with res delete with flap closed and with flap open.