I had a Cobb and it isn't much louder than the factory exhaust. It has a slightly deeper tone. I changed to a VSC exhaust which is louder but has manageable drone below 90 mph.
I thoroughly enjoy the COBB catback. Just a touch deeper than stock, which was near perfect just needed some grunt. Anything louder would make me feel like a boy racer, tbh.
Recently (last Thursday) installed a Cobb CB on my 22. Exhaust notes are sweet but frankly, a bit too groanny inside the cabin for me especially at rpms above 3K. Cobb doesn't feature a resonator. Resonator sound clips with a Cobb CB online don't seem to make much of a difference even with Ultra Quiet Vibrant resonator. Thinking about going back to OEM exhaust. Anyone interested in a relatively new Cobb CB at a very competitive price!
I'm still on the fence between aftermarket and one of the STi muffler sets. I've read posts of some dealers who are getting very picky regarding aftermarket parts and warranty coverage. I doubt they could have any objection to OEM accessory parts sold by SoA. Sorry to hear of your drone/groan experience with the Cobb.
I'd suggest you post your location and perhaps a price on your Cobb setup, as shipping could be a dealbreaker.