Even on race gas, depending on timing I still would not tune for 12:5 most I would go for is 12:1. Tuning for 12:5 is still pushing it IMO. I would still go 11:5 tops 12:1 because he is still using the stock motor. I would always keep it as safe as possible with making enough power to be happy. Why tune for MAX power when it will only shorten the life of the motor anyways. 11:5 is safe for a stock motor even on pump or race gas, and can make good power. Whats another 3-10whp and pushing the motor more then you have to? If he had different pistons that could keep up with the extra heat maybe 12:5 but again 12:1 is safe on race gas, again this is just IMO.