[oldman]

thanks, makes sense, I have to look into the retainer part number (hence I added the question mark on that one). I went to a solid stem, undercut head Manley Proflow so it fullfills two rolls: stronger, better flow, the Titanium fullfills two rolls: stronger, lighter. I have still valve springs anyway, but if I was going DoD crazy with boost, I would have sprung for the slightly more expensive LT4 intakes.

I show this LT4 intake only valve retainer12654813, so this retainer in use with the LT4 valve must bring the same spring used in all applications to the correct spring height, I wodner what the slightly longer valve does, I assume it is for tip to rocker alignment. The longer valve in theory going from memory would move the contact out board of arm given a slightly increase rocker ratio and quicker opening along with slighly more lifter load, of course this would require slightly more closing pressure which GM gets by using a way lighter valve... hm intresting.