Hi guys, i'm back again as i now have the funds for the s4 and a few mods. I was wondering whether anyone would be able to help/recommend a few bits that i'm looking to upgrade straight away. Any help is appreciated. 1. Re-circ DV 2. cat back + 200 cell cats 3. Recommended oil to use? - as i've seen a few companies list 10w40 and some listing 5w30? Also i'm going to get a BMC CDA as they seem to be the best kits for a few of my friends cars, but if anyone has a cda or any experiences with them regarding the s4 please elaborate. Thanks in advance guys!