need help with exhaust

[sm32589g]

i want a meaner sound out of my 1999 323is i removed the butterfly valve which made it sound a little bit better but i want it to basically free flow. but the problem is i dont want to disconnect my O2 sensors and i dont want my control panel to read error messages or anything like that. please can someone tell me what i can do to improve my exhaust.
P.S. removing the butterfly valve added like 1 lb-ft torque more ha, could be mental though. it feels quicker for some reason.

 

[frolf]

hate to say it, but removing the butterfly robs you of some low end grunt because of the lack of back pressure.

 

[Big Daddy]

So true and if you want a more throaty sound than you need to get a performance muffler.

 

[sm32589g]

REALLY? i plugged up the hose with a screw it is connected to the intake manifold. i mean routed not that one hose. it feels quicker tho. idk ill try putting it back on. but then that is contradictory to replace the muffler would still be even further reduction of back pressure. wouldn't it?

 

[sm32589g]

rrrriiiggghhhttt????

 

[Big Daddy]

the Active Exhaust System Actuator (AESA). The AESA consists of the following:

Exhaust flap with vacuum actuator
Solenoid actuator valve
Vacuum reservoir with check valve
MS 41.1 control module
The electrical function of the exhaust flap operation is controlled by the MS 41.1 module.

At idle speeds, up to 2500 RPM: the exhaust flap is closed with vacuum applied to the actuator. This causes the exhaust gas to pass through the long resonator pipe, reducing the low frequency noise that is generated.

Above 2500 RPM: the exhaust flap opens. This allows the exhaust to pass through the short pipe which maximizes the back pressure effect to provide the best performance.

In the event of electrical or vacuum failure the flap will rest in the open position providing maximum exhaust throughput.

The valve remains in the system with a performance exhaust..."rrrriiiggghhhttt"

 

[sm32589g]

that still doesnt answer my question though does it add power or now?
another note: i was thinking about buying a stock M3 cat and gut it than add a performance muffler would that help eliminate the O2 sensor lights? or other warnings on the computer? thx.

 

[Big Daddy]

When I read it it answers the question!

 

[grc]

the AESA improves low speed drivability. it opens automatically when more power is needed/desired. it's a variable volume exhaust system.