i wouldnt agree that arp only do it to cover their asses. realistically those studs do stretch. not as much as tty bolts but any bolt or stud will stretch especially at the torque levels we put these heads on.
proof look at the assembly instructions for any arp hardware on rods...
i think the case is that even with the stretch tool steel isnt going to back out enough to make a serious difference on heads.

 

ya, you are correct they will stretch but the engineers for ARP know that even without re-torquing them they will hold. It's been proven with almost every person in here. Shops don't even do a re-torque because that requires the whole front timing covers to be pulled off. It's 6 hours of labor that nobody does and nobody has issues.

Now with TTY on the other hand, they stretch considerably so I would be very hesitant to install them without doing the final re-torque after running the engine. I know for a fact that BMW is required to drive the car then re-torque all their TTY (which is every vehicle).

The good thing about ARP though, once they have stretched they won't stretch any further so if you re-use them then no reason to worry.

 

Pretty sure you know how they work but this statement looks funny. Once they have stretched after proper torquing, they spring back to their original length after disassembly. Then you can install them again and re-stretch them.
TtY spring back to almost their original length, but not quite, because they have been plastically deformed. If you reinstall them, they are, ironically a bit stronger than they were before as some strain hardening occurred while they were stretched. Unfortunately, this comes at the cost of elasticity and the bolt is now much more brittle than before.

 

That's why I have used l19's Nothing to do with being a broke *** kid!

 

ya, I wasn't very proper in how I explained it.

I mean the initial stretch from being brand new. There is always some amount of stretch when putting load on them. They won't stretch near to the degree of a TTY bolts since TTY are designed to actually stretch.