Some insurers will load for a modded car, some won't insure at all.
I have in the past tried to insure a mondeo that I put a recon engine(I did) in, they said modified straight away, even though it was 100% std apart from 0.5mm oversize, and wanted to load 60%, that was Privelege, spoke to(one of) thier underwriter lady and she said treat as normal.
tabetha