BERK HFC's.... Gasket between cats and exhaust mani??

atx370z

I have been having issues with raspiness with my Berk HFC's and Stillen CBE... im 100% sure i've got all the slip joints 100% sealed up and that helped the sound a lot... but im still getting some rasp around 4k to 5k rpm. I crawled under the car and noticed that the shop that installed the HFC's only used some sort of sealant between the HFC's and the exhaust manifolds. It's orange color and im sure it's some sort of high temp sealant. The shop works on Ferrari's etc. so i trust they know what they're doing, but is there supposed to be a gasket there or is the sealant sufficient? That is the only other place i could possibly be getting some "leakage".

All other bolted joints have gaskets and are super snug!

Thanks in advance.

__________________
Berk HFC & CBE, Stillen G3's, AMS Crank Pulley, JWT Flywheel,
4.08 Gears, UpRev, H&R Springs and 20mm Spacers, JDM
Rear Fog, EVO-R Front Lip and CF Upper Cover, 305's