My 2wd Saff is lowered and the S/S centre box scraping on speed bumps etc was a pain so years ago I had a custom made oval shaped S/steel box made. It still allows a good flow but sits up nice and high and never scrapes on anything. I have recently had a new one exactly the same made by Maniflow in Salisbury. It wasnt cheap but is very high quality and fits really well.The rest of the S/Steel exhaust is not a problem. All the big bore aftermarket S/Steel exhausts all have a round centre box which is to big.