[Lozmate99]

Pardon my lack of knowledge. I have been trawling the net for info but its all very conflicting and I can't get a grasp on what I want to do. I want to increase hp and get a more sporty sound. Can someone point me in the right direction. I also don't want to spend a silly amount of money.

1) New cat less downpipes with high flo 2nd cats. - still pass emissions test in uk? Will this gain much with a ecu tune and stock exhaust. Recommendations as to what products I could use? Will exhaust note change alot, also don't want the dreaded drone.

2) same as above but with non stock exhaust. Again can you recommend products? want stuff that will all fit without to much hassle.

3) Remove cats completely? stock exhaust? But then i got the hassle of getting it through mot.


Cheers.

[J02 335i]

JB4 and muffler delete, sounds great and loads of power. Also very cheap.

[DirtyD]

In before JDLM thread relocation

[335xi_zer0]

1) New cat less downpipes with high flo 2nd cats. - still pass emissions test in uk? Will this gain much with a ecu tune and stock exhaust. Recommendations as to what products I could use? Will exhaust note change alot, also don't want the dreaded drone.
I'm unsure of UK emissions test, is it OBD, Dyno, and/or visual? As mentioned above, a JB4 or any of the tunes available for that matter will seriously increase your performance. Have you tried the golf tee mod? It creates a deeper more throaty noise at cruise and is completely free. Downpipes will DEFINITELY give you some more rumble to that noise. If you have an OBD test, I believe you will fail unless you have a dpfix mod. The high flow cats will help, but with Downpipes and exhaust, those cats will eventually fail.

2) same as above but with non stock exhaust. Again can you recommend products? want stuff that will all fit without to much hassle.
If UK inspection is visual, you will fail. They will spot that the non-stock exhaust does not have any cats (ps our cars come with 4 cats). There are plenty of exhausts that come recommended up the forum, just search around (AE, Eisenmann, etc.).

3) Remove cats completely? stock exhaust? But then i got the hassle of getting it through mot.
Why would you remove the cats completely? You would do so getting new DP and Exhaust anyway. Removing the cats wouldn't serve any other purpose than what they are meant to do.

With all that being said, if you have the time and want to put in the effort to remove your DP and exhaust and return to stock before every emissions inspection, you'll be fine.

[Lozmate99]

with Downpipes and exhaust, those cats will eventually fail.

Cheers for replys. So am I correct in understanding with no cats in the downpipes the other cats will eventualy fail. So a sensible idea would be high flow cats in the downpipes? Any sugestions? AR designs?

[enrita]

Originally Posted by Lozmate99

with Downpipes and exhaust, those cats will eventually fail.

Cheers for replys. So am I correct in understanding with no cats in the downpipes the other cats will eventualy fail. So a sensible idea would be high flow cats in the downpipes? Any sugestions? AR designs?

I run AR dps catlees with stock secondary with no issues for 2 years tuned.
just get the dps and a tune like cobb or jb4.
With that setup i passed emissions in italy . I than put 100 cell race cats in the secondary and pass emissions in sweden . Both with sniffer.