wow $99 per??? fuck. thats so much more than the diff between the trackpipe for OBD1 and 2. wow. im floored. i have the 02 sensors and i can vouch for power gains, with a dyno graph. im not sure about the safe mode, but i talked to Rennwerks a while ago, and they basically told me that anything other than stock is likely to mess with things, even if it is only to a slight degree.