20+ Psi coasting

[BigRAWesty]

The cat wont fix your issue. I dont see 20 psi as an issue aswell. If it were 10psi i would.

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It's not really an issue no, but it's not wanted.. happy with stock.
But the cat will assist the lack off back pressure and that has to be only reason why it's over spooling while coasting..
Not sure if it'll fix it or not.. I'm hoping it does but if not then it'll be valves to take control..