Does anyone know of a place / shop with an SPL meter where I can pay for an hour or two, bring my car in and tweak and tune accordingly ?

 

Do shops even do that kind of thing ??

 

Yes, some do. The bigger shops out there 'should' have the equipment you are looking for. Just phone and ask what their price might be to rent the meter for an hour. You would have to do it there probably, but $50/hour is a safe assumption.