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[TheBoy]

LOL, could you have made the pictures any bigger

That will be horrid to drive, too peaky.  Maybe fine when I was 17

Any turbo is easily tunable - just keep whacking up the boost until the engine breaks.  Problem with smaller engines, is as you up the boost, the low down torque goes, hence the nasty, thrash-it-everywhere, turbos such as Renault 5, RS Turbo etc that are awful when chipped up, unless you are ragging everywhere.  

Omega is too heavy to have a peaky engine in.

So if I was to turbo an Omega, I would start with a bigger engine, ie 3.0l

[Kevin Wood]

Any turbo is easily tunable - just keep whacking up the boost until the engine breaks.

Absolutely So many people forget that everything that applies for tuning a NA engine applies in equal measure to a Turbo engine. Yes, you can turn up the boost, fit a bigger turbo, etc and get more power at the top end but, as with all engine tuning, you lose something elsewhere.

Also, when looking at Turbo torque curves remeber that in real life that torque is only available when the Turbo is spinning! Torque output on a V6 is there as soon as the throttle's open!

A mate of mine bought a Westfield with a Cossie Turbo engine which had all the toys, a very well regarded chip tuning package, bigger turbo and was allegedly making 340 BHP or so. It had massive lag and a horrendous step in the torque delivery right in the midrange which made it feel 'kin fast as the boost came in but in reality it was undriveable on the track.

He took it back to first principles, ported the head, fabricated a better inlet plenum, fitted a correctly sized turbo and a decent engine management system that can do proper closed loop boost pressure control. It now really does make 340BHP, at half the boost pressure as previously required, it's much quicker, runs cooler, and has a lovely flat torque curve.

The other issue is refinement. The V6 really is so much more refined than a highly strung turbo 4 pot would be. Fine, if the car is only for racing that doesn't matter but for road use I know what I'd prefer.

Kevin