"The Duttweiler (is that the name??) car used the stock valves and made over 300hp".
Actually -COMPLETELY DIFFERENT RULES for a turbo (he made 450HP, BTW). The guys (racers) that have made 250-270 HP on a N/A 2.5L (Chris Reinke, Al Mirko, etc) all used big valves, higher CRs, hotter cams, and 8000RPM redlines. This is what makes me think that to (possibly) hit 250 HP with a stock CR - you will need to reach high into the rev range and need all the breathing & cam you can get. All tied together with a carefully dyno tuned ECU program.
But good luck. I certainly could be wrong & hope to hear of excellent results. I have little doubt that youll get significant gains with a good P & P/valve job combined with thoughtful intake and exhaust mods.
