93 octane Mark D'Sylva chip can I run 91?

[Hoffbrohaus]

2 PO's ago a Mark D'sylva chip was added. The PO I bought it from said it was a 93 octane chip but he had it reprogrammed for 91. I opened up the ECU today and the chip is truly in there with 93 octane written on it.

So my questions are: How can I tell if it was reprogrammed? Can it even be reprogrammed, I would think you'd have to swap the chip? Is it ok to run 91 octane on a 93 octane tuned chip since we don't have 93 in AZ?

[603Racing]

The only way to get a definitive answer is probably to have it checked by someone that does that sort of thing.

[Hoffbrohaus]

Emailed Mark D'Sylva himself. we'll see what he says.

[digger]

alternatively choose a hot day fill up a quarter of a tank of 91 then drive it and see, the old m20 in stockish form is not a high compression or FI monster that will suddenly explode if you use bad fuel for a little while oreven if runs a little lean.