My exhaust is as loud as that and it does drone in the cabin. Passes the MOT no problem. They do note exhaust loud. Initially seriously considered changing it to stock. Lexus wanted £1500 for stock exhaust! Over a year later I'm glad I didn't. Believe me it is very loud. Gets a lot of attention ... Sometimes unwanted! But when I use the paddles, the downshifts and popping sound so good. Unfortunately before I get asked, I haven't a clue who it's made by. All I know is its a custom made one for the last owner. Asked lexus to contact last owner several times but nowt yet. Luckily for me my neighbours love the car. Just as well as I can leave for work at 3 in the morning