Nice to see a non cossy Sierra getting some attention. With a ported and polished head and some cams I doubt it made 180bhp. I been messing around with these engines for years and the only way to get that power from them is to fit a turbo. The upper limit for a non turbo is about 150bhp, and that's having everything possible done to it. They do however, have good low down torque. If you can get an engine loom from a car with a cat, or if you already have one, you can fit the injectors from a Vauxhall 2.5 V6, which are much better and can cope with other upgrades you want to do to the engine. Good luck with it, keep us posted