Hi you can upgrade i did my last 308 feline. GT line rear parts were about £270 you don't need the tow bar blanking plate as it comes already on the diffuser the gti parts are about £400 from what i remember.
Hi it's easy to fit. The GTI one should fit ok when i got the GT line one for my car i was told they both fit. When i fitted mine there was torx screws near the adblue tank to undo then you put your hand up behind the bumper and release the push in clips round the diffuser and it then it pushes out from the bumper.
Thanks for the info I have ordered the GTI diffuser, give it ago. The seller says that the tailpipes diameter:
Holes are around 9,5 centimetres so I think 8 / 8,5 centimetres pipes will fit.
PDC holes have to be drilled.
i will await its arrival before ordering tailpies hopefully they will just 'snap in'
Legend if you happen across any images would really help me!