Hello - I am Jake Wiebe, inventor of the SureGrip Cylinder Head Stud Kit (US Patent #8,740,532) and owner of Northstar Performance.
Certain types of repairs on the Northstar only have a hit/miss chance of working. With our repair kit, success is guaranteed. The only car I managed to blow the head gaskets a second time on, was my 1997 Eldorado ETC. The composite head gaskets blew out from the repeated runs to 130MPH. That was our test car so it saw a LOT of abuse. none of the studs had failed and all were still tight, no thread fatigue or failure. So for racing applications I recommend multi-layer-steel (MLS gaskets) and our SureGrip studs on the Northstar. We sell the MLS gaskets as well from the Flat-Out Group. We did have one other failure, due to a head imperfection (a nick across the fire-ring sealing area, that I had missed) and due to that it slowly pressurized the cooling system).
Going with our kit I personally guarantee success or the money back on the kit (ask me the details). It works WAY too good for anyone to second guess it. I'm not saying that to brag- I'm saying that because I know the problems Northstar owners face and I've made it my life'* work to eliminate the chance of head gasket failure on these engines. We've fixed over 600 Northstars to date in our shop and our kits have been used by other technicians since 2009 with great success. GM Warranty had approved the use in one car, that I know of; and asked the dealer to keep a couple kits in stock.
That'* a beautiful SSEI there damadtech in your signature. I have a 2000 (recently had an accident with it) and now a 2004 GXP. Great cars!
I hope to be of help and potentially a site supporter/advertiser.