Let's just keep at that the power curve could indeed be better, and that you might speak about a slight amount of turbo lag. But I think it is manageable.

I'm going to quote some LM GTE rules from wikipedia, as I think the would fit this category pretty well (scaled down of course): - "The engine displacement is limited to 5.5L naturally aspirated or 4.0L turbo/supercharged." - "Carbon fiber, titanium and magnesium are banned except for special parts like spoilers or wheels." So would say roughly 1.8L turbo charged or 2.5L naturally aspirated. I think you can get roughly the same amount of horsepower with them, both having completely different statistics. With respect to carbon fiber being banned, I would suggest to ban it for everything except for the wheels, same goes for titanium and magnesium seeing as they are banned from real high performance racing as well. Regarding emissions and noise, I think there should be limits on those, however I did not yet spend to much time trying around with those, so I don't know what is reasonable or not. I don't think there should be any restriction on fuel efficiency or reliability, however I do think there should be a maximum octane value. I'm thinking about 95 RON.