This might not be for everybody -
but for those who think the cabin noise in an Elise/Exige is a bit too much there is an easy way to make significant improvements.
In a stock 2009 Elise SC cabin noise was reduced by 6db, from 91db to 85db by applying something called GLADEN AERO-Multi on the rear bulkhead and under the seats.
It does of course add some 5kg to the car, but if cabin noise is a concern then it is probably a small price to pay.