Not quite right. As a true bolt on your correct.Thats basically all we can do right now with out 4.2 engine. Unless you have a few thousand dollars to drop for a custom turbo install along with trying to tune it.
What can be done is basic hot rodding - port the cylinder head especially the exhaust ports and camshafts.
I have done both, with lower compression (8.2:1) than stock 10.1:1 I made 353 HP on a '06 engine at 6700 rpm.
With stock compression this would be even more power.
Cost wise it your can do the installation work yourself:
head - roughly $900 including a good 3 angle valve job
cams - cam blanks $570 + 500 for finish grind. (or 400 + 500 if we get 20+ people on the group buy now underway).
Add a re-tune on top to optimize the install.
