I think having modifications probably would make it more expensive to insure that a standard cupra. I have a bog standard Ibiza Cupra mk3 and I have enquired and modifications shoot the insurance through the roof, but maybe that's just my scenario.
Not true. if you get quotes from specialist modified car insurance companies you will find a modded 1.4 is MUCH Cheaper to insure i.e. I'm 18 and have a modded 1.4 and pay £1200 with everything declared. a standard cupra, not even a ICR would cost me Well over £5-£6000 easily. This is my scenario granted and your insurance company obviously don't favour modded cars hence why yours will cost more
My Dad had Continental Sport Contacts on his Astra SRI, not sure which particular vararity, but he rated them highly, not cheap though.
My dad runs these on his XK8 and rates them too! and no definately not cheap in 19"