Well I finally had the car tuned with the TD-06 etc and was doing really well at 16psi. I decided to up the boost to 18psi and before even another quarter of a psi was added the head gasket failed. Hmmm oh well time for a decent metal one I guess. My question is what is the thickness of the standard one and which metal one is the best to put in to keep compression the same?

If I'm not mistaken, a 1.2mm multi layer would be suited to your application

Thanks, after some research it appears that a metal head gasket are not that easy to find online. Can you get them through Burson, Autobarn etc? What is the approx cost (200-400)? Does the block and head need machining?

Nothing should need to be machined, and yes I feared that the stock of parts would be the killing price factor
But. http://twosrus.com/catalo...31&products_id=691
Here you go, 95$ which is good, I paid $430 for my 1.2mm tomei ML metal HG for RB20

You neex to have the head checked. It generally needs to be machined to have a perfectly flat surface for a metal head gasket.

Hit up gorilla inds for a cometic hg. Theyre only 100-150.

your crazyyy if you fit a metal HG and dont machine the head, its asking for trouble as they dont flex or compress as much as the normal ones do so even a tiny bit of warp and it will leak again. get it done right the first time so you dont have to redo it again..
 
as for metal gaskets you can buy Cometic ones from ebay or from autobarn from memory or gorrila can get you one as justace has suggested
if the head is being shaved/machined then add that thickness to the MHG to even it out and keep the compression the same. (im pretty sure the MHGs comes in a few different thicknesses)

Get a metal HG & ARP head studs to be done with it. Unless you see any nasty surprises when the head is pulled off.

i think you will find you will need to get the head and block mechined i had mine done and im not using a metal gasket but its more off a prevention then a option

Also what pistons are you running?
Is the motor a GEN 2 or 3?
What future mods are you planning?
How much boost in total do you plan to run?
 
Depending on what size gasket / pistons you have will affect your compression ratio.

I have the gasket and head sorted (had it machined) and is being installed today. Gen 2 standard bottom end rebuilt approx 20,000kms ago. Probably wont push it past 18psi. I have forged pistons and rods to put in a second engine when it gets more serious.