hi
I think the good choice will be the S3, I have seen APR insturction, they remove the complete front panel and headlamps to do it, I dont wish to mess with it.
Removing the bumper is no problem, Can you remove the intercooler without removing the front panel 
Thanks
Nope. You do need to remove the headlights to take the slam panel off though, and there is a crash beam behind it too actually, but it is all just nuts and bolts.
As memory serves from the 2 I have done
Remove bumper - disconnect fog light wiring and piping to headlight washers.
Remove Slam Panel and headlights
Remove crash beam
Remove screws from core assemblies and support A/C core
Disconnect core piping
Remove OEM core
And put it all back with S3 core.
Once you have done one, they are easy.
Be sure to order screws to fit the S3 core as the plastic screws used on the GTi core are plastic as the core ends on the GTi core is plastic, and the thread is different. Also be sure to order S3 pipes as the connections to the cores are different.