There are many companies in the UK who will make you a custom built cat back stainless steel system, seen them on ebay for my LS400 with a dual system for around £500.00.
I recently purchased a nearly new set of 18" alloys ( German made Rial Catania ) with as new Rainsport 3 tyres for £300.00, found them on Pre-Loved so check out ebay, Gumtree.
You need wheels with a PCD of 114.3 5 stud, offset 35-45.