Originally Posted by hawksview
I would be a little careful with this one. The highest octane rating i have seen for unleaded is 104. The rating of 125 tells me this is leaded fuel. The main advantage to running higher octane fuel like this is to run more timing which means you really have to tune your car on a dyno. You may see a little advantage but without an engine tune it won't be much. Running leaded fuel will eventually take out your o2 sensors and plug your converter. I ran 104 in my stage 3 srt4 when i would switch it into high octane mode with the turbo toys kit and the difference was unreal but like i said the HOM button advanced the spark to handle the extra octane. Personally i wouldn't do it.
I agree with hawk... Don't do it. You will do more harm than good as it's probably leaded fuel that will potentially void your emission systems warranty if used too much. Without something like Stage 3/toys on the SRT4 to advance your spark, the extra cost and octane really won't do you much good. I too have an S 3/toys SRT4.