is cam timing. You can see the one I posted holds power much better at the top because the cam timing is more optimal. The little bit on the bottom is not worth the sacrifice at the top. Stock turbos are tiny and the bottle neck, better heads with such small turbos will not net a lot more IMO. It is truely amazing what we do squeeze out of stock turbos, we are already pushing them harder than they should be. If you want that power, you want larger turbos that are not working so hard.
