Hertsdriver, can you suggest a better alternative than stainless based on your experience?
Correct me if I'm wrong, but it looks like you're saying that using stainless fixings is a bad idea because of some stuff you found on the internet. The original Porsche fixings are made of plated mild steel. Their dissimilarity to aluminium means that there will always be galvanic corrosion of both materials. If you change one of those materials to one that doesn't corrode (yes, yes, I know stainless does corrode eventually, but for practical purposes it will last 10 years on an exhaust) then you leave yourself with half the corrosion problem that you would have had. Given the mild steel bolt will corrode as well as the aluminium bore it's in, the two will mechanically lock themselves together and at the same time as weakening the bolt. When torque is applied to the bolt it frequently take more torque than the weakened bolt can withstand to undo it. Ping! I heard that ping on nine out of twelve manifold bolts in the last couple of days. :nooo:
If you've used a stainless bolt, the corrosion of the bolt won't happen, so the mechanical locking won't happen, and the bolt will be pretty much as strong as the day you put it in.
You also say that stainless is softer and therefore is harder to drill into if the fixing snaps. This doesn't make any sense. If softer materials were harder then I would make a hammer out of playdough.
Sorry if any of this comes across as confrontational, it's just that having just spent three days skinning my knuckles underneath my car, partly in the pouring rain, it really grips my sh!t when people who haven't done the same (and I'm assuming you haven't, so apologies if you have) give bad advice based on hearsay. The consequence of this is that some poor ***** out there in the real world could read it and choose to either spend a fortune on wonder-bolts unnecessarily, or worse, install the original Porsche hardware, which will corrode to nothing in a few short years.
I use stainless in all sorts of applications across my 911, and having done this for six years, every one of the stainless fixings I've used has done its job and not caused the hole it's been screwed into to corrode beyond use. I've lost count of the mild steel fixings that I've had to drill out, hammer out, snap off, etc. I'll continue to use stainless based on my experience with it until someone comes up with a tested equivalent that works better and is reasonably comparable in price. If the stainless fixings I've used come back to bite me in the bum and my helicoil skills can't save me, I promise to come back here and own up.