What about the Jdm hatched stumbling after you have mapped them Martyn? And still stumbling
mine was the same amongst other issues never stumbled once when it was standard
I’ll put the oe ecu in the bin and stick with the syvecs

It's funny over the pond this gets mentioned loads and Cobb and Perrin both think they know why.

https://www.cobbtuning.com/products/...-sti-2008-2019

On a side note, people seem to be getting the wrong end of the stick.
I'm not saying you should all rush to remove your aftermarket ecus and put your stock ones back on. Somebody made a statement about being able to run more ignition advance on a Syvecs than you can on a stock ecu. This is not the case, so I replied saying they were incorrect and elaborated as to why they were incorrect.
I have not said there is no benefit to going aftermarket and even went as far as saying that we are big fans of aftermarket ecus including the Syvecs.
Nobody needs to get their knickers in a bunch lol