I've fitted 3 TRC splitters at this stage, 2 to a Leon FR and 1 to my Cupra. same procedure for both. I really should have done a DIY instruction post on
how to do it last time. I've tried the self tappers by themselves and I ended up having the splitter get ripped off the car at 180km/h from the force of the air resistance alone. That prompted the 2nd fitting. This time it was bolted on and it's was fine till I sold the car, got a Cupra in April and bolted on another one. The cupra has gone to 235km/h and it didn't budge. You can bolt it on WITHOUT removing the bumper, it's fiddly and is way easier with a extra set of hands. A set of jack stands is a must before you work underneath the car. A splitter is not worth getting crushed to death for lads. Safety first. Halfords sell a 2 tonne set for about €30.
You have to remove the two wheels and front section of the wheel arch liners, no need to remove the section directly above the wheel, this is only a couple screws. Get under the car and loosen the plastic sump guard or remove it completely. This is only a few screws as well and its 2 pieces of flat thin plastic. This will give you access to the inside of the bottom of the bumper. I used 3 self tappers to align the splitter and hold it in place, get someone to
help you line it up with the arches and put one tapper through the pre drilled holes on either side and one in the middle(center of the bumper). This will make life easier when you are drilling. If you dont have a drill or self tappers just tape it in place. Now drill holes big enough to take the supplied bolts, they're M5 i think, through each of the splitters pre drilled holes.
You can now just feed the bolt up through the holes and you should be able to add the nut to each bolt either through the arches for the side ones or from directly under the car for the front 3. It's tight for the center 3 but its doable, a small hand will
help. Just bend the underside of the bumper down and you can slip your hand into this space where you will find the bolt sticking up through the bumper. It is tricky to get the nut started in the bolt. A spanner on top of the nut and an allen key bit in a drill to wind it down quick once its on the end of the bolt does the trick. Do this for all 9 bolts. The splitter is now fitted so just re attach your sump guard and arches and you're off.
Total time for myself and my dad to get this done the 3rd time was about an hour from jacking it up to lowering it back down. Removing the front bumper is defintely not the easier way to do this unless you plan to do some other jobs like painting the grill/license plate area and bumper below the grill at the same time.
I well have to see this setup in the flesh to wet my appetite some more. Both diffuser and exhaust on my shopping list, just got to figure out how to gwt them ordered and delivered undetected by the misses 
