Gerry,
It has been discussed before, there are a few TM users interested in tuning the duratec but I have not talked to a plus-4 owner who has done it yet. I am on the fence, upgrade to a roadster or tune the plus-4. A tuned plus-4 could be more fun and cheaper. As I understand it; in order to get more out the duratec you need to improve the induction system. In order to match the injection with the improved airflow and get a propper set-up you will need a programmably engine management unit. This has put me off for now, at least until the warantee has run out. I guess you can fit a sport exhaust and a chip but I don't think you will get a noticable increase in power, maybe more noise and fuel consumption. If you are serious you could talk to Chas Windridge at Mogsport. He has done a few thottle body & EMU conversions (180 bhp) and gets good reports. Be prepared to pay serious money for serious HP. If you do go for the chip option please let us know what the results are. I think you would have to put it on the dyno before and after to be sure about the gains. Long story
hope it helps.
