Reading up on ls1howto on the manifold install..it says i will need...
1x 2001+ LS1/LS6 intake
- 1x 2001+ front coolant pipe - #12568478
- 2x 2001+ rear coolant plugs - #12562788
Will i have to purchase these in order to install the intake? Or can i use what i already have from my ls1 manifold?

 

Yes your factory lines will not fit under the LS6 intake. You will see once you get your ls1 intake off. So you have to buy the plugs and the new pipe for the front. Also be careful for the oil pressure sending unit on drivers back side of the intake.. the brake booster line tends to snag it and break it.

 

Or just grind the tabs on the bottom of the LS6 intake, there is another post on here with some pics of grinding. Let me see if I can find it. Grinding - FREE or new coolant lines around $40.

 

Here you go: https://ls1tech.com/forums/showthrea...ght=intake+ls6

 

i would get some intake seals to they arent expensive

 

Just use a chisel and hammer, chip the ridges off the bottom, and then you won't need to touch your current coolant lines.