Sorry for the belated reply. I did read it with good intentions but then got side tracked..
No never did consider the 2.75" system purely for the reason you mentioned. .
In my eyes my old td42 had 25 years and over half a million k's on the stock zinc exhaust..
We run oil burners.. so unless your in the salty drink often I can't see the need for stainless..
So yea went the Playtime 3" system.
Yes and no mate..
I have fitted the 200cpi stainless cat which is higher cpi than what Dea and Playtime fit. They only fit 100 cpi ceramic core cats.
But unfortunately it hasn't resolved the issue.. It's made an improvement, I'm only seeing over spool to 20 ish psi not 26 psi. That's on the scangauge reading calculated readings.
But Tillix is on its way soon to rid the issue..