When I bought my Cup it had a Ktec exhaust with no middle silencer and it was just horrendous. Constant noise. At no point did it sound good, it was just noise. I've fitted an OEM system which was about £100, though they seem a bit fragile to be honest.
Otherwise, mine has a couple of poly bushes, some Eibach Pro Line springs and Continental road tyres and it's bloody brilliant to be honest. I use it for plodding around in as a cheap daily, and it is huge fun on the track too. Really capable little car that surprises a lot of much more expensive machinery.
You will have a lot of fun in yours, I guarantee it!