I dont think it will make much difference, the upper shield is on and closer to the rubber hanger. Most if not all, aftermarket exhausts for the NSX dont have any heat shield and mounted the same.
I dont think you would want to replace the entire exhaust just for the heat shield....... not priced at £2,131.83!!! and that doesnt include new tips which are £298.63 each!!
Total of £2,729.08 for complete new exhaust!!:eek: