what are average gains from upper/lower hard kits?

 

Lower is only part that you really seen power gains. Upper depending on which you get will help spool up but even that is debated. I would go with a LICP kit first and pick up a small battery and UICP later on. I recently picked up the AMS LICP and a LPI UICP since I want to keep stock battery. If you do a search you will find a ton of info.

 

A lower pipe MAY yield 5-7 whp or so at the very most, but spool will be improved by a few hundred rpm's.

An upper pipe doesn't provide as much of a noticeable improvement, but can't hurt.

 

My hard pipes made a throttle response difference and highway power

 

do you need a tune or no if you do a full icp set. also adding a biger fmic. thanks

 

Only do a LICP if you have supporting mods. It will make no difference and even possibly hurt performance unless you have other items that improve flow -- such as a TBE