VT V6 hotting up

Hi, I have a VT commodore V6 ecotech, It has 16" rims, a modified throttle body, a high flow cat, and a slightly modified manifold a K&N filter, and i have taken the snorkel thning off the airbox, so now it breathes through the hole in the bottom of the airbox. it runs 15.6 now. I have ordered some yella terra roller rockers with 1.8, which should give more lift. so does anyone know how much difference this will make? also what is a good way of getting the air intakes good on these cars? i have heard that cutting the bottom of the airbox is good. any ideas? What are SS inductions like? any help would be good, thanks.. and if there is anything good and easy you think i should do let me know. thanks

Ey i have a VT aswell, by the time you spend all that money on it you might aswell get a V8 and you will have a faster car without even doing anything! Its not worth doing all that work as resale you wont get anywhere near what you will have spent. Any ways.. SS induction is MUCH better i have a mate who put one on heaps more air flow, but not sure if it effects performance. If your willing to spend money get a supercharger as it should add an extra 30-40 kw. I wo9uld get a set of 17 or 18 inch rims and lower it aswell, nothing worse then a car which has had work and looks like a boat with small wheels. What do you mean by you have taken the snorkel off the airbox? where did you put the K&N airfilter caus i once tried putting it on but it didnt fit. good luck.