OK, I stuck the splitter onto my rear bumper. Which was very difficult as it really didn't wanna fit right. After a lot of struggling I got it into place left it to dry overnight. The next day I realised it wasn't 100% perfect. If you look at the images below you will notice the right hand side sticks out about 1cm further than the left. Not really sure what to do about it now. I think I am just gonna finish smoothing it in, then see if I can somehow with a bit of DIY pull it in slightly, or push the other side out slightly.
What do you think?