Hi and welcome. First things first, dont bother turboing your 1.6. It will be a higly waste of money for the power you will get back. Bear in mind that Vauxhall have played around with the 1.6 engine in the Corsa VXR to hit 186bhp which is huge for a 1.6 engine. I understand you want to keep your 1.6 Astra so why not just think about an engine conversion. The 2.8 8v Turbo Kit is fast becoming popular as the 2.0 8v is virtually bulletproof. You can snap the cambelt and it wont bend the valves