It wont be that loud, its a European version or sth (apparently there are 3 versions, of which the Japanse one is the loudest, the US one doesnt fit coz it doesnt leave space for the cooling fins of the rear diff which isnt on the US models, and the EU one). Its only a few db louder than stock, but deeper.
As he said, if i wanted one which makes lots of noise, i should get a HKS or APEXI
I think it will be fitted correctly, as the guy is the only one in Belgium doing Nismo stuff and regulary does engine tuning and thinks like that, so i guess he can mount an exhaust straight