Ok, Kat, for the stretch bolt part, I'm gonna make you read something that was already written. http://www.gomog.com/allmorgan/stretchbolts.html This pretty much says it all.

The carbon on those/that head and piston actually looks pretty good. Thanks to fuel injections and computers. You will almost always have something left over after burning a fossil fuel, hence air pollution

We never said that it/they was a "stretch bolt"... On my side of the conversation, it's just common practice. Weak link of the chain kind of deal. Our machine shop figures that if the bolts have been through untold number of vibrations, wear, tear, heat cycles, over heat cycles, cool cycles, etc. Best practice is to replace.. The end decision will be yours.

Interference engines? Last thing I knew, the 3.5 was an Interference Engine.


Non-Interference


Valve/Piston Interference

For the most part, even if it wasn't an Interference, I wouldn't take any chances. I had a '88 Acura Integra 1.8 Non-Interference with 300k on it. Lost the timing belt, the was just enough carbon built up on the piston and valve that it cracked the head from the collision anyway. They may be non-interference from the factory but will it stay that way?