Thanks mates.

I donīt want someone can call me a "boyracer", but also I donīt whant to put a small or ridiculous exhaust on my Rst S2.
I choose Mongoose because Iīve got a good price offer.
I never ear the sound of Mongoose 3.5" or 4" tailpipe fitted on a Rst.
How much is louder 4" than 3.5" tailpipe??