I want to get this info out to anyone whos willing to listen so I can save absolutely anybody I can from going through what I did.
I made the mistake in April of buying a Bootmod3 tune for my F56 Cooper S, I used the OTS 93 octane map without being aware of the problems it will cause. I used it for around 3 months without issue until XHP released their TCU tune for the 6 speed Aisin. I flashed stage 2 on July 3rd and by July 4th I had lost compression.
Why did I blow my engine? Because the BM3 OTS maps target insanely high boost and is only PARTIALLY kept in check by the EGS limiter, which XHP removed. With that limiter being removed my tune started targeting 25+ PSI. For context, at stock a 11:1 CR Cooper S B48/b46 will run 8-10 PSI of boost.
Remember when I said partially? That was on purpose, the BM3 OTS tunes even with a stock transmission tune will overshoot boost at spool and during shifts. I logged the tune on my engine for a short while just to see what it was running, and I discovered the engine spiking boost of 20-23 PSI on shifts and spool, insanely dangerous on a Cooper S engine on pump gas. Not only that, the boost curve in general is really bad, overshoots at spool, and tapers really fast in the mid range where you actually want the power.
The boost control isnt the only part of the tune with a problem though, the rated octane for the different OTS maps are basically wishful thinking from BM3. At WOT on the 93 octane tune was pulling around -6 degrees of timing and experiencing a knock event, almost every pull. If you were on the 91 tune running 91 Id suspect the same thing probably would happen.
Im on a JB4 now and it makes better power up top, and doesnt overboost like BM3 does. Kinda crazy that BM3 makes a ECU tune worse than a piggyback for the same car. Thats my rant, I just would hope to save anyone else from making the choices I did and end up with a 5k+ repair bill.