So, I've replaced headstuds with the engine in the car before, but only catch this time is that the headgasket is an MLS.

Can I still do the one-by-one headstud swap? Im going from regular ARP's to L19's.

I have done that many times, just take your time and do one by one.

Even with an MLS gasket? I've done it with an OEM gasket, but just want to be sure.

Thanks!

The gasket shouldn't make a difference. The idea of doing it one at a time is that you never really relieve the clamping pressure between the head and block.

Consider re-torquing them after a few hundred clicks as well, I would think the MLS would be less forgiving if the L19's do have some minute amount of stretch after they've been installed and heat cycled a few times.

Actually, re-torquing is a big misconception, you can over stretch the studs and ruin their integrity. ARP recommends to torque to the proper value and leave them. There was a video out showing how much the torque value can be off if you re-torque them.

Arp molly and 90ft-lbs of torque on my l19's and they have been reused 3 times now and haven't lifted at any point.

I thought the whole reason 2G guys got l19s was because they did not stretch?

Every bolt stretches when they are over torqued.

We mainly go l19 because our headstud are a millimetre thinner and therefore can't hold as much.

That's fine, what I'm stating is when someone throws the torque wrench back on them while they are already torqued down, all that is doing is over stretching the bolts.

Standard ARP's can hold their own, I've ran 30psi on my setup but I know they're probably coming close to the limit. It's all about the tune, a really aggressive tune with ridiculous cylinder pressures or loads of knock will life a head at much lower air flow.