Exhaust noise

What is your question?

At low speeds the exhaust noise is embarassing - is really loud; during most highway drives there appears to be normal exhaust noise (might just be obscured by wind, etc)? Have had two shops examine exhaust system and have found no problems. Any ideas? Also, the "brake light circuit" comes on frequently for no reason; may be off for days/weeks at a time then be on steady for a couple of days - any ideas on this?