I'll second the 42's and 80mm pro-m, seen that combo on a few cars. I'm building a 306 for a friend now (TFS TW, P1-SC), and it'll have the 42's. We would be ok using 36's but they are more expensive than 42's. Try to buy for a combo you might have later instead of having to get larger injectors when you do upgrade, but what power do you expect? How much boost will you want?