I am starting this thread in response to my own car having slow down light issues after installing aftermarket exhaust components. This should also help people having troubles with thermocouples or thermocouple ECU’s on stock or other configurations of exhaust. I will be posting information I find while looking into this and learning more about the thermocouple system. It may also morph into a way to eliminate the thermocouples and thermocouples altogether and keep the computer happy. This will be focusing mainly on the 1996-1999 355’s with the 5.2 Motronic system. The 1995 models are not as picky and from what I understand may be easier to defeat the slow down light (I have not read much on the 2.7 because I do not have one). This info will also be good for many other cars that use the same Thermocouples and/or ECU’s. The part that makes this tougher on the 355’s is that you also have to contend with the by-pass valve thermocouple. If you would like to read what led me to this point, feel free to read this thread: http://ferrarichat.com/forum/showthread.php?t=377790 For tonight I will be starting with this: I am going to first measure the supply voltage going into one of the Thermocouple ECU's. I expect that it will be at battery voltage 13.8 V or so (I will refer to this as 12V from now on if it is). It was hard to tell on the schematic where the supply was coming from once it hit certain module blocks with vague descriptions so I am just going to measure it for myself (faster than staring at schematics and I do not entirely trust the WS manua)l. I will then pull the module and a thermocouple from the car so I can just work with them on the bench. I will apply power and ground to the module and connect volt meters to the output lead. I will leave the thermocouple attached to the ECU. I will then attach the thermocouple to my adjustable soldering iron (goes up close to 900ºF). Then I can change the temp on the probe and monitor the output voltage right at my electronics bench where it is easy. I will even be able to dial in an exact temp and see what the output is for future possible simulation. I can then pull all three systems and make sure they work the same. This will tell me a lot as well as test my components to make sure they are all working right in the first place. I have a good idea how I can build a nice simple module to eliminate all this stuff once I figure out what the computer wants to see in all bypass states etc. So, I am off to the garage. I will post back when I have some more info.