Noo - Autodelta sell a complete straight pipe kit anyway? Should sound sweeet!
Maximum is 96 decibels at tick over as I am aware - I doubt they will test it anyway!? I was driving around in my Alfasud with a tasty straight pipe exhaust at Goodwood with the Lancia club strangely - on driveby they tested me and found to be 101Db and that was with my high lifting 1350cc boxer engine on 36 Delorttos and standard airbox, before I change it for an 8v 1751cc boxer on Twin 40 Delorttos and 6" Volocity stacks and socks and side exit straight pipe with no mufflers. Goodwood only had planning permission for 104db unless the Maserati club were out on track racing who had exemption.
If an AC Cobra with a big clumsy V8 with side pipes can pass - I am sure an Alfa GTV with a straight pipe can
Alfa Autumn Blast! Zig Zag 2. - YouTube - mine was third down hill and the famous alpine road Zig Zags in Shaftsbury - this was my little 1351cc engine and Ansa exhaust not side exit straight pipe.