Hey daz08 - Installing FIT 1.9 Rockers is easily reagrded as one of the:
"Very Best Modifications" you can do to your Ecotec V6 !!
it makes a significant and noticeable difference all the way from idle to redline and gains are even further amplified if you have Exhaust, Extractors and CAI.
Check out the following link for Dyno Results:
http://www.v6supercharged.com.au/rocker.asp
Hope this helps.
Regards
Tonsta