Secondary cat delete or resonator delete
 

Hey I have a 08 535i with AR catless downpipes and billy boat axle back exhaust. I'm trying to get my car to sound a bit louder and was wondering if i should delete the secondary cats, resonator or both and if I would lose any power doing so.

i have the e60 530i,,, which has a close engine sound to yours.. maybe event the same... i have a remus axle back... i first removed the cats... i barely noticed any difference... but let me explain to u thoroughly cause i tested out many setups..
1-sec cat delete: no increase in sound (maybe barely).+ hp increase (were talking 2 hp) +engine breathes better (mine were clogged so imagine it with out them :P) + popping sounds when shifting
2-resonator delete : louder sound... and i mean louder by a lot.... in a nice way....

if i were u i would remove the sec cats first... ill notice louder sounds since u already have a downpipe... if u still think its low... then off with that resonator... and add an x pipe... ...
PS u can always weld the resonator back... so no loss..
tc bro and tell me how it goes...plus send me a vid of ur setup...my friend has a 335i and is researching an exhaust system...

Delete everything! :devil:

So if you delete the secondary cats you won't pass smog since you have ***less DP's already. If you are looking for more sound deleting the resonator will do that. Just be aware you will have drone at freeway speeds.