Mmmm bugger sounds like you have got those couple of things covered. The only thing trying to do the tk test as doug pointed out to me it is not the easiest thing do to after after a couple of boosted runs is not trying to burn yourself with coolant or him for that matter.

The simple version is that the Cosworth ones have a folded layer in them between the gasket layers.
It means they have a little bit of give in them. A margin of error if you like. They will allow the heads to lift slightly before failing or rather more so than OEM gaskets.

I originally had Cosworth studs but wanted the peace of mind that the 14mm ones offer. They have a much higher clamping force over a bigger area.
I'm aiming to Run 30psi all the way to 8000 rpm so I will need all the extra strength I can get.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds

I'm looking forward to this. Not!!! Haha My mate has the kit to do the test.

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MY06 STi

The Cosworth gaskets sound good by your description Daz. See~ing as Im not power hunting the Cosworth studs should be enough for my setup aswell. Reliabilty is what I want without having to open the new 2.5 Short Motor up...

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MY06 STi

I think the Cosworth studs are fine for 99% of applications.

I know a couple of cars running them that are circa 800 bhp although they are on 2.35L (stroked EJ22T).

I went for 14mm studs because I simply had the opportunity to do so. You'll have no issue running Cosworth or ARP 625s 11m studs and Cosworth gaskets.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds

Hang on, weren't you the one suggesting cosworth were horrible to deal with and not worth the time??

If you need a head gasket, genuine STi MLS. Anything else is just wank.

ARP 625's AGAIN............

Great way to waste $800 in an application that does not warrant them.

I must have missed all the lifted head threads where people were using ARP 2000's?
I only know of 1 motor that actually lifted it's heads - and that was Tino's monster!

Head studs won't fix bore resonance - I'd be pinning the top of the 2.5's bores before throwing Primo Guucci head studs at it.

BTW I do rate the 625's - I just fitted a set to an RB26 that makes 950hp, they are just complete wank on mild builds.

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[CENTER][SIGPIC][/SIGPIC][/CENTER]
[CENTER][COLOR=#ff0000]Built Ej207: Semi-closed RA Cases - Wiseco Forgies - Manley rods - BC 272 cams - GDA Heads - billet f/whl - Vi-pec - WbO2 - 800cc Yellow tops - TD05-20G - 409Hp ath @ 1.75bar on E85[/COLOR][/CENTER]

Make that 2...my old '06 STI lifted its head (and it was only 216 KW ATW)...rebuild was done with ARP studs (and STI head gaskets) and the car was fine for at least 3 years after....
Darken's sounds like exactly what mine did...after the initial issue there was no overheating etc....pulling the engine down will also allow a ringland check...

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No Subarus currently owned

Spot on Nauli. My STi came with receipts for a build back in 2011. Brand new STi short motor installed. It's lasted roughly 3 years and has only done about 75kms since then. The work was carried out at Subaru Wangara. This build included OEM head gaskets and ARP studs. Not long after that the car spent time on the Dyno at Maximum Motorsport. Hence why I think I should go down the Cosworth route. This may prove to be a safer/stronger option with the Cosworth Head Gaskets and Studs. I'm just going by readings/findings.

Now with what you have just said Nauli. It just just reinforces me to try a different option from OEM head gaskets and ARP studs. Btw what ARP studs did you use?

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MY06 STi

I said Cosworth themselves were horrible to deal with not that their stuff is shite but as far as head gaskets go I would only use them, Tomei or RCM ones.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds