If you only seeking an easy to install M3-Look-Exhaust ... you should take an look at the german company Insideperformance
... in their shop you get this parts (prices are incl. 19% german VAT!) !
OR as an very cheap alternative lock in the CSR shop ... the have all parts to convert your e90 in to an complete M3-clone ... the exhaus you find at http://de.csr-shop.info/public/catal...uctid=19150481