N54 Motor w/ N55 Midpipe Real HP #'s?

[theinfamousdrew]

Currently I'm running:
Catless downpipes
N55 mid
Stock exhaust.

This setup has made my car pretty raspy (sounds like my old M3) and obnoxiously loud at start up and for the first 15 miles or so.

Has anyone with catless downpipes actually dyno'd with and without catless mids?


I'm thinking that if I put the stock midpipe back on it should tone down the noise a bit while only loosing minimal HP.

[BrokenVert]

A resonated midpipe would solve your problems

[theinfamousdrew]

The n55 is resonated.
Im saving up for an intercooler at the moment so Im looking for a cheap solution for a month or so.
But if I change it back and there isnt any real power loss then Ill be fine with it.

[BrokenVert]

It is? Hmm always thought that the N55 was straight mid.

nevermind

[theinfamousdrew]

It has no cats but still a resonator

[BrokenVert]

Originally Posted by theinfamousdrew

It has no cats but still a resonator

Are you talking about the little thing just before the Y pipe?

That things sucks - you might want to try a real resonator.

[1speedbike]

Originally Posted by BrokenVert

Are you talking about the little thing just before the Y pipe?

That things sucks - you might want to try a real resonator.

+1, that fart box BMW calls a resonator doesn't do much against rasp.

Try a midpipe with individual resonators in each pipe, like Maddad or Berk. Berk's resonators are bigger Both are tuned to help eliminate drone and rasp.

I just installed raceland DPs with a Berk midpipe and street axleback. It's raspier than it used to be, but not bad at all. Not nearly what I was expecting. Going catless on these cars always adds at least some rasp.

[SixBanger]

Will the N55 mid-pipe installed to an N54 with just an axle back add power or just noise?

[1speedbike]

Originally Posted by SixBanger

Will the N55 mid-pipe installed to an N54 with just an axle back add power or just noise?

If you take out the catted N54 pipes, you might gain like 5, maybe 10 if you're lucky, HP depending on the replacement pipe. The build quality of the pipe matters, so the smoother the bends in it, the less restriction to the airflow. The cats do restrict the airflow a bit, but removing them is not like the 20-30 horses you'd unlock with downpipes. Well, that also answers OP's question... which I forgot to do in my first post haha. InfamousDrew, you'd only be losing 5 HP, 10 at most, going to a catted midpipe. The downpipes are where the hot, turbulent air needs the space the most.

[Colt]

My setup I have is deep....not raspy....I do have to agree on it being a little loud though. Might do the Berk mids and axleback down the road

[SixBanger]

Originally Posted by 1speedbike

If you take out the catted N54 pipes, you might gain like 5, maybe 10 if you're lucky, HP depending on the replacement pipe. The build quality of the pipe matters, so the smoother the bends in it, the less restriction to the airflow. The cats do restrict the airflow a bit, but removing them is not like the 20-30 horses you'd unlock with downpipes. Well, that also answers OP's question... which I forgot to do in my first post haha. InfamousDrew, you'd only be losing 5 HP, 10 at most, going to a catted midpipe. The downpipes are where the hot, turbulent air needs the space the most.

What if I replaced my stock with the OEM?

[theinfamousdrew]

Originally Posted by 1speedbike

If you take out the catted N54 pipes, you might gain like 5, maybe 10 if you're lucky, HP depending on the replacement pipe. The build quality of the pipe matters, so the smoother the bends in it, the less restriction to the airflow. The cats do restrict the airflow a bit, but removing them is not like the 20-30 horses you'd unlock with downpipes. Well, that also answers OP's question... which I forgot to do in my first post haha. InfamousDrew, you'd only be losing 5 HP, 10 at most, going to a catted midpipe. The downpipes are where the hot, turbulent air needs the space the most.

Thanks! I was thinking that it didnt make too much of a difference.

Originally Posted by Angerman

My setup I have is deep....not raspy....I do have to agree on it being a little loud though. Might do the Berk mids and axleback down the road

ok, what is your setup?

Originally Posted by SixBanger

What if I replaced my stock with the OEM?

Yes you will gain a bit of HP just by adding the N55 midpipe and even more when matched with catless downpipes.

With stock DP, stock muffler and the N55 mid you gain slight throttle response, a few horses and a deeper tone with only a slight increase in volume.

[Zombie1]

Originally Posted by 1speedbike

I just installed raceland DPs with a Berk midpipe and street axleback. It's raspier than it used to be, but not bad at all. Not nearly what I was expecting. Going catless on these cars always adds at least some rasp.

are there any videos of this set up? Love to hear her!

[Dackelone]

N55 vs N54 mid pipes...



The main benefit with using N5 mids on a N54 engine is faster turb spool up with a small increase in power. 5~10hp most people say. And an increase in exhaust "bark".

[Gumball]

I run ar catless down pipes, n55 mids and stock muffler and installed 2 small resonators on the n55 mids in the same position as the cats on the n54 mids. Before installing the resonators it sounded horrible at anything but wot. The rasp with the windows down was so annoying and sounded crap from the outside. After getting the resonators it sounds much the same as with the n54 mids.

This topic has been covered on e90 post a fair bit. I think the brand to buy in the usa is vibrant.

[Lambobimmer]

I am running catless DP's, Maddad midpipe, and Maddad whisper axelback and it sounds great. I think that you will lose power if you go back to the stock mids.

[1speedbike]

Originally Posted by Zombie1

are there any videos of this set up? Love to hear her!

I'll take one when I can! It sounds great, not too raspy at all. After installing the DPs, it sounds the same at warm idle (a little louder cold) and when lightly pressing the gas. But now when you push the gas harder, it feels like the exhaust is really opening up and letting out a roar! Best way to describe it, I think. Plus, the turbos spool so much more readily and quicker, and there's almost no lag in the response any more. And this is with shit $200 downpipes.

[SteveAZ]

So, if I understand this right and feel free to correct me... But isn't the big advantage other than a few horsepower gain in replacing the down pipes with catless the fact that if you install an upgraded FMIC you can now run stage two and that's where the big HP and TQ gains are?

Also, does the cooler oil temps help with carbon buildup on the valves?

And one last question...has anyone done the catless down pipes with otherwise stock exhaust and had any problems with emissions?