I have just driven across Europe in mine. It booms. But it also sounds amazing in and out of the car. I have driven behind it now and wouldn't want it any quieter as it wouldn't be that audible to other road users 
Through the tunnels it sounds unreal
JJ, if you are worried I think you should stay with the standard or switch to the original issue K-Tech which changes the sound but without making it any louder. I guess you could add more soundproofing to the engine bay/covers if it comes back still too noisey? Just seems like a lot of hassle and cost for something you don`t sound too keen on and have no way of predicting the outcome?
I think I am going to heat-wrap mine when I get back. I have really noticed the effects of heat-soak in the car on this trip. We must be loosing a lot of power though the heat that is retained in the engine bay.

Through the tunnels it sounds unreal

JJ, if you are worried I think you should stay with the standard or switch to the original issue K-Tech which changes the sound but without making it any louder. I guess you could add more soundproofing to the engine bay/covers if it comes back still too noisey? Just seems like a lot of hassle and cost for something you don`t sound too keen on and have no way of predicting the outcome?
I think I am going to heat-wrap mine when I get back. I have really noticed the effects of heat-soak in the car on this trip. We must be loosing a lot of power though the heat that is retained in the engine bay.