dude as im doing the same project (cg10de turbo) i shall give u a word of warning!
U will struggle very very hard for insurance as i have shopped around and cus its a modifiaction that increses the bhp of the engine the insurers cant put a price on such a random thing hence i only got 1 quote which is 1,800 fully comp and im 20 with nearly 4 years no claims! as u are 18 it will be well over 2 grand so u are best off either not doing it or waiting until u are 19 and insuring it thrid party!