Peugeot 406: STW success vs. BTCC failure

[matherto]

Personally one of my favourite shapes of the 90's, the 406 design leant itself very well to a Super Touring makeover and as such both the STW and BTCC cars looked fantastic in their various liveries.

There was a vast gap in performance and success between them though. STW was great for Peugeot with Aiello winning the title and generally always being competitive with Van Ommen as well but the BTCC team forever struggled despite Watts, Harvey, Radisich and so on being pretty decent drivers.

Does anyone know why they were so radically different? Surely they were effectively the same cars or did the STW team build something completely different?

I know they were Peugeot Sport cars whilst the BTCC cars were ran by MSD (I think) or others so did they have secrets to unlock that they didn't tell the boys in Britain?

I read an article somewhere that the STW engine was pretty similar to the 306 F2/Maxi engine and with MSD running Hyundai's effort in the same class, they didn't want to give away anything, perhaps that's true?