Given I chop and change between towns, one with eflex and one without I was just going to stick to a 98 tune due to issues of having to drain fuel when I change over every time I live one town for the other. I've been thinking and from what I gather the main problem is on the 98 tune if there is a few litres of eflex in the tank it will run the risk of leaning out and going boom. What is the chance of increasing the afr's on the 98 tune to say 12.5-13 (or higher?) in order to compensate. Ideally it would be best to run a wideband and eboost to keep an eye on things but I didn't realise how expensive they are. Most likely going to stick to 98 so this is more of a theoretical question, but just curious as to whether someone has done this/whether it could actually work