[A26B]

Originally Posted by Matt B

So... Is that still a potential issue to all 375HP LT-5 that run with OEM cat?

E.g. when I bought mine the left cat was crumbled and had to be replaced.

Just out of curiosity. I don't think it's a common issue as up to that day I never heard about it.

Matt,
I don't think it's a common issue at all. As I understand catalyst reversion, it may occur when the engine is operating @ high rpm, throttle is closed and clutch is engaged. Think in terms of road racing and using the engine for braking, i.e. engine braking.
As Hib stated in his last post, "lower pressure in the cylinder." I think it's likely negative pressure, occurring on the downstroke. The intake air is shut off when the throttle closes, and exhaust reverses direction, flowing towards the negative pressure on the downstroke, picking up catalyst "dust" on the way.
I don't imagine it takes long, considering the high rpm. Likely not a good idea to be at very high rpm & just dump the accelerator. Engine braking during heel-toe is generally in the mid-range of rpm.

Not an expert by any stretch and just my 2 cents, so I will probably draw some flaming.