[jamesm]

CIS is a pretty good system, but like Dave says, it won't tolerate cams that are much wilder than "very mild". On the 911 engine at least, more than about 70d of valve overlap causes the car to idle very poorly, and surge throughout at least the bottom of the rev range. Duration of more than 230d on the intake may also cause problems. These cam timings cause lots of pulsing in the intake tract from pressure waves, and the CIS airflow sensor bobs around like a cork in the ocean, drastically altering the mixture at a set throttle opening.

I've also heard the water-pumper VW types claiming they use wilder cams with CIS, but I don't know how much "wilder" they are. Probst's book on Bosch FI claims wilder than stock can be used, but there's an unspecified upper limit before problems occur. Porsche never used anything other than very, very mild cams with their CIS-equipped 911 engines, even on Euro models, so I'd be surprised if you could go much hotter than the above numbers.

The nice thing about CIS is that it's very simple, and automatically adapts to changes. Other than the cold-start system, it's all mechanical. The cold-start stuff does tend to be the weak point.

Another alternative is to get a new wiring harness for your D-Jet. There's a place called R.E.S. that sells complete aftermarket harnesses for the injection system that appear to be high quality.