just wondering if the stock cat might be causing the heat build up as it doesn't flow well, would replacing it help?

bump bump bump

Dunno. It's theoretically possible that they might, but only way to be sure would be to measure radiant heat with the stock cat, then compare that to the radiant hear of a high flow cat.

Maybe check with Maurice (CanZoomer), who is the only one I can think of that would have the capability to do this on separate cars simultaneously. Or maybe call Random Tech and see what they say... they might have measured this.

Another possibility is RX8Husker or Shebam, both of whom have HF cats + Borla exhausts. I'll have my HF cat back on the car next week, and I'll see if I notice a difference.

Hope this helps. At least it's better than no responses at all... ;)

Ive had mine on for about a week... I thnk that it is a little cooler

well the best way to reduce cabin heat would be to insulate it from the cat itself.

catalysts ain't cheap, so it may be cost effective to go with the extra insulation.

I'd never thought about this, but entirely subjectively, I 'd say -- YEAH. We've had some hot patches and I do think the cabin has run a bit cooler this summer (perhaps the heat's been converted to noise :)). Of course, the engine bay, the PCM box, etc. are still broiling after running and take a super long time to cool down ....