Brad Maynard

I may be looking to change my intake manifold set up on my C5 and was interested to understand:
1. if the LS2 or Ls3 type manifolds are significantly better than the Ls6 set up.
2. Can the Ls2 or Ls3 work with Ls1/Ls6 and if so, what needs changed or modified to make it work. (including any connections for wiring or if I would need to use the newer type injectors and fuel rails, etc etc.).

Gray Ghost GS

Trust me - you don't want to replace an LS6 intake manifold with an LS2, which doesn't flow as well. I don't think an LS3 intake manifold will fit on an LS1/6 block (not sure). The LS6 will support up to 500 hp - ask me how I know. I finally moved up to a FAST 90 intake manifold, but the LS6 was doing very well. If your C5 is a 2001 or newer, then you already have the LS6 manifold - enjoy and save your money. If you want to improve throttle response have your Throttle Body ported and polished.

Brad Maynard

I currently have a modified LS6 (it has the supports cut out of the inside and is ported), and a basic polished/ported TB. I thought the new ones had better flow than Ls6 so that is good to know if that is not true.

I would prefer something with a stock look over a FAST if I can get something close performance wise.

I suspect that my TB is much more limiting than my intake on my current set up.

Gray Ghost GS

You can send your LS6 intake manifold to TPIS and have it modified to accept a 90mm throttle body for $350 or to LPE for $369.

Brad Maynard

So what TB would I need to get after that? Would it be a stock Ls2 type?? Are they 90mm? Or some aftermarket one?

I wonder if they would want to modify one that is already modified in other sections than the front? (to cut out the supports on mine, they cut out the bottom and re-made the bottom). Guess I can explore that as a possibility.

Gray Ghost GS

I use a LS2 90mm TB on my 383 LS6 (with FAST 90 intake). Works great.