Post Master General
Join Date: Apr 2012
Location: Bowling Green, VA
I Ride: '09 ZX6R
No direct experience, so it's all anecdotal.... if I had to guess, I'd think any aftermarket can would not be as insulated as the OEM can. Hence, more heat under the seat. Airflow is a crucial part of the cooling process -- if someone adds an aftermarket module under the seat area, and that blocks airflow (which is already substandard IMHO) and adds some amount of heat as well -- when you cap that off with the heat from the catalytic converter burning off the excess fuel, into a less insulated muffler system I can see how it may end up hot enough to start breaking down the ECU. The cat would burn off more, if a fuel enricher is in use, as more would make it out of the cylinder and onto the cat.
The typcial solution is to replace the '05 ECU with one from an '06. As I have no idea if there is any physical difference between the model year ECUs, I have to wonder how successful this approach is. You don't hear anywhere near as much about '06 having this issue, so there's some real possibility of a change.
Were I to buy an '05 in need of TLC, I'd probably start with gutting the catalytic converter. That's going to reduce the exhaust temp by quite a lot of degrees. It will stink more, and may appear more sooty at the tip of the muffler; if it's cooler exhaust that can only be good for the ECU. Next, I'd add some heat insulating tape on the side of the tray facing the pipe, to reflect away as much of the heat coming up off the pipe as possible. Make that patch wide enough to let the heat find another path up, that does not include penetrating the tail section.
If the '05 OEM ECU acts up after all of that, I'd get a used '06 ECU, if one can be found.
"Basic stuff fellas. Use your head for something other than to break your next fall."