[DHMerks]

if i were to get catless headers for my n52 and keep my secondary cats will there be a strong smell or do the secondary cats help minimize the smell with no primary cat.

[jbash87]

You won't notice any difference. I have this same setup on my E60M5. You will need a tune, however, to make use of the freer flowing headers and get rid of the pesky o2 errors.

[DHMerks]

Originally Posted by jbash87

You won't notice any difference. I have this same setup on my E60M5. You will need a tune, however, to make use of the freer flowing headers and get rid of the pesky o2 errors.

oh nice! and gotcha thanks yeah the smell was kinda the deciding factor for me with those lol and yeah ik i need a tune i was looking at the stagefp tune since ppl say that is a good one to get but im not sure if it will get rid of the o2 errors tho.

[Leucosticte]

Originally Posted by DHMerks

if i were to get catless headers for my n52 and keep my secondary cats will there be a strong smell or do the secondary cats help minimize the smell with no primary cat.

Smell isn't bad unless you're idling somewhere for a while.

[oVeRdOsE.]

the moment you keep a cat, the smell will be fine.

On my car I always used high flow cats, and never had smell like a test pipe will do.

[DHMerks]

Originally Posted by oVeRdOsE.

the moment you keep a cat, the smell will be fine.

On my car I always used high flow cats, and never had smell like a test pipe will do.

yeah i was looking at buying the performance headers that roundelwerk sell.

[mictang]

I recently bought a set of these from AliExpress after seeing another post about them on one of the Z4 forums.

The headers I got (~$300 plus shipping) look exactly the same as roundelwerk's pictures, whose website claims they ship directly from the manufacturer, which probably is from China.

Build quality was average/decent, or worth the $300 price tag at least, nothing top end but fairly solid material and welds are good but not perfect. Install was not hard except one or two bolts that were hard to get to compared to stock.

I am pretty sure the original design was from AA (which in turn was inspired by super sprint, I believe).


As for your original question, my car is euro spec (no secondary cats), there is no smell while driving around, but can be unpleasant idling in underground parking lots and occasionally at stop lights with a tailwind. The difference compared to stock(usually a light fuelly smell at idle) is very noticeable. That being said, if you don't idle much, shouldn't be a problem.

Oh the sound is very good, nice burbles on lift-off, very satisfying, which landed me a ticket once (measured over 120db with my BMW PE muffler).