Double head gasket??? No no no no......
Let me get this straight.....
Youíve got a 280 BHP engine running 22 Psi and you want more power (who doesnít?)
You think the right (or easy) way is to run a higher turbo pressure.......
And then you realised that a higher pressure means, a (much) higher air temperature giving more chance of detonation and ruining your pistons/engine. So lets get the compression down and lower the strain on the engine.
In my (not so humble) opinion it doesnít work this way. Donít lower the compression and lowering compression should never be done with double or thicker head gaskets.
1- The German site www.C20let.de says: NEVER use double or thicker head gaskets, also never use anything else than the original opel/vauxhall gasket, others will blow through sooner or later.
2- Lowering compression gives less engine efficiency. So you want to loose 10 or 20 BHP with the lower compression and compensate with extra boost?
3- Youíll need an extra high pressure to compensate the efficiency loss, so the air temperature will even be higher giving extra detonation problems.
On the Wallace-site they say people shouldnít mess with the turbo pressure. This has something to do with the ECU. It canít adapt to the higher pressure and so will fail to give the extra fuel that is needed. (read what they say a the phase III-kit)
This could be just a story to have people buy tuning parts they donít need, but Wallace isnít the only company that says it. Yeah, true this could be an international scheme to sell tuning parts, but I think thereís some truth in it.
The phase III kit doesnít come with a thicker/double gasket so it isnít needed. Yet they do run a higher pressure.....
Oh, I can almost hear you thinking ďheís the only one saying donít do it, heís wrong, why does he think he knows it all?Ē
Well, Iím not an expert on this; Iím just combing eight years technical school, some engine mechanic theory and info from the internet. So, donít believe me but ring Wallace (or an other tuning company) and asked what they think.
Summary: DONíT do this; go for the phase III upgrade..