Catless downpipe Questions? please help

[BeachM5nster]

I will probably buy active autowerks catless downpipes but if anyone knows of a a better brand or a reason to go with another please let me know

but my Questions here are:

1) How difficult is the install? should i get dealership to install or can just a muffler shop do it? (is it hard to access?)

2) will catless DPs foul my O2 sensors or decrease their lifespan, should i just get new sensors along with the pipe?

3) Should i remove the resonators that are in the mid-pipe section of the exhaust?

any other knowledge on this appreciated.. a guy on here said a catless stock M5 is same as a stage1 with cats... so im just gonna go catless to avoid messing with bmw's stock maps bc i want to stay stock in that area

[AWF10M5]

You could just gut your stock cats for the best fitment and sound.

I had aftermarket ones on my last one. the fitment wasn't good and required cutting the heat shield and the o2 sensor would burn out because of the way they sat.

This time I gutted the stock cats. Perfect fitment the sound is great and no o2 sensor issues.

I never tuned either so you will always have a CEL on. Catless downpipes and the resonator delete is the best sound with little drone.

[Rocketsoda]

Originally Posted by BeachM5nster

I will probably buy active autowerks catless downpipes but if anyone knows of a a better brand or a reason to go with another please let me know

but my Questions here are:

1) How difficult is the install? should i get dealership to install or can just a muffler shop do it? (is it hard to access?)

2) will catless DPs foul my O2 sensors or decrease their lifespan, should i just get new sensors along with the pipe?

3) Should i remove the resonators that are in the mid-pipe section of the exhaust?

any other knowledge on this appreciated.. a guy on here said a catless stock M5 is same as a stage1 with cats... so im just gonna go catless to avoid messing with bmw's stock maps bc i want to stay stock in that area

I gutted my stock downpipes a few months ago with my buddy. Rented a lift in a garage, had torx bits and o2 sensor socket. Took about 5 hours to get the pipes out, gut them and put them back in since the car had been up to operating temps. Overall super happy, and it's not a difficult job at all

[BeachM5nster]

Originally Posted by AWF10M5

You could just gut your stock cats for the best fitment and sound.

I had aftermarket ones on my last one. the fitment wasn't good and required cutting the heat shield and the o2 sensor would burn out because of the way they sat.

This time I gutted the stock cats. Perfect fitment the sound is great and no o2 sensor issues.

I never tuned either so you will always have a CEL on. Catless downpipes and the resonator delete is the best sound with little drone.

what brand downpipes did you have if you dont mind me asking?

[AWF10M5]

Originally Posted by BeachM5nster

what brand downpipes did you have if you dont mind me asking?

I had vrsf in the past. Definitely do not recommend them.

I'm 95% sure the cheap ones on eBay are the same exact ones as VRSF. Wouldn't be the first time.

[G-M5]

Go gutted oem if you can. I just got them installed. Zero issues. No rattle. Fits perfectly.

[BeachM5nster]

Originally Posted by G-M5

Go gutted oem if you can. I just got them installed. Zero issues. No rattle. Fits perfectly.

i have ordered a set of 76mm meisterschaft DPs. I'm curious to see if they fit and work well

[_BSMM5]

Originally Posted by AWF10M5

You could just gut your stock cats for the best fitment and sound.

I had aftermarket ones on my last one. the fitment wasn't good and required cutting the heat shield and the o2 sensor would burn out because of the way they sat.

This time I gutted the stock cats. Perfect fitment the sound is great and no o2 sensor issues.

I never tuned either so you will always have a CEL on. Catless downpipes and the resonator delete is the best sound with little drone.

I just installed some Ebay downpipes.. the fitment was actually pretty good except ONE O2 sensor (driver side Pre cat) which was off by what seemed 1 cm, couldn't get it to thread in, so had to trim the heat shield a little. I was worried about the heat messing with the sensor, is this what you mean by burn out?

I have a muffler delete, and after catless I really don't like the sound, Sounds great in the low end but in the high end it has this tin can/raspiness. Will deleting resonators help with this?

[BeachM5nster]

Originally Posted by _BSMM5

I just installed some Ebay downpipes.. the fitment was actually pretty good except ONE O2 sensor (driver side Pre cat) which was off by what seemed 1 cm, couldn't get it to thread in, so had to trim the heat shield a little. I was worried about the heat messing with the sensor, is this what you mean by burn out?

I have a muffler delete, and after catless I really don't like the sound, Sounds great in the low end but in the high end it has this tin can/raspiness. Will deleting resonators help with this?

putting muffler back on. cutting out resonators will make it worse

[Dwaynos]

Originally Posted by _BSMM5

I just installed some Ebay downpipes.. the fitment was actually pretty good except ONE O2 sensor (driver side Pre cat) which was off by what seemed 1 cm, couldn't get it to thread in, so had to trim the heat shield a little. I was worried about the heat messing with the sensor, is this what you mean by burn out?

I have a muffler delete, and after catless I really don't like the sound, Sounds great in the low end but in the high end it has this tin can/raspiness. Will deleting resonators help with this?

Just do the resonated x pipe as done before on here.

[M5Rick]

Poor 'ol standard exhaust is really getting mutilated here.Just get an exhausmeister lol

[Dwaynos]

Originally Posted by M5theonlyone

Poor 'ol standard exhaust is really getting mutilated here.Just get an exhausmeister lol

I did a back box mod last week and did a ghetto exhaustmeister today
Very happy, thread on it's way.

[M5Rick]

Originally Posted by Dwaynos

I did a back box mod last week and did a ghetto exhaustmeister today
Very happy, thread on it's way.

Yeah I saw that, your handy with a cutter and welder.
It looks tricky to weld up boxes because of their thinness.

[_BSMM5]

So I had actually only heard the exhaust from inside the car and it seems that tin/can raspiness was just my imagination (That doesn't make sense at all, but I rode in a different car with a true full exhaust on it, and what I described as "Tin can" sounding was there too, so I guess my definition of "tin/can" raspiness was actually just the way a loud exhaust sounds through all the sound deadening)

Also rode in a buddies F80 M3 with an MPerformance exhaust and let me tell you, the S63TU straight piped sounds FAR better.

The sound deadening in the vehicle really changes what you hear on the inside of the car versus the outside. So I had my buddy rev and do some pulls in my car and from the outside I loved the sound. There is a bit of drone but to be honest no where near as bad as the drone on my old 535 or 335 due to awesome sound deadening in the M5.

The exhaust is quite loud, but if you've spent any time around ANY american muscle cars its no where near as loud as those vehicles straight piped. The turbos in this thing really round off the sound.

I'm still on Bootmod3 which only offers a mild burble or aggressive burble, but not a tune with NO burble. Really not a huge fan of all the pops and cracks so I'm trying to get a custom tune to cut that out. With that in mind, potentially installing 200 CEL cats in the midpipes would kill all the pops.

Heres a video.