ok well for the cams to truely be effective in giving more power you need to make sure they are shimmed to spec, an you could rebuilt the motor and put higher compression pistons in it to really unlock some power. but with the increase in compression two things will happen.
1 the high comp. ratio will increase the cylinder pressures which will cause pinging or predetonation and to fix that you will have to retard the timing easy fix but you also should run a higher octane fuel too.
2. with the higher pressures comes with higher heat given off. so upgrading the cooling system is a must. start with radiator and thermostat, then get some nice silicon hoses.
"is this one of those fancy double twin cylinder motor automobiles?..... i love me some xs042's.. if god drove an import we all know it would be a xs042."