Ahh well, I checked the insurer's website, and I think being robots without a single piece of car-knowledge, they don't differentiate between exhaust parts. They just tick new exhaust system >.<
So I guess I'm sticking without the backbox until October when my no claims comes round. Can't believe how much my insurance went up though once I passed my test.... increased the balance by £322.14 for the REMAINING 5 months! Such a rip! Technically costing me £2700 annually........
My brother's insurance on his Grande Punto went from £1800 down to £800 with 1 years NCB, so I guess I can hope!!