Power: Catless vs Stock

[bmw13]

Option #1) removing only the secondary cats

Option #2)fully catless

Option #3)Stock

My car is stock and most likely will stay stock. Would option #1 or #2 benefit the car in any way? - or is it simply a noise increase. I feel like the car is set up a certain way and I am afraid to upset that. But if I can go a little louder while staying stock for the most part, and only benefit the car from doing so, I am all for it! So if any of you engineer-type-people want to enlighten me feel free, PLEASE

Will going this route to go louder affect the overall performance? I will not sacrifice performance for sound... But if performance can only benefit, the louder exhaust in return is just a plus! Any help/ enlightenment is much appreciated!

[fourtailpipes]

catless is almost universally more powerful. loss of backpressure sometimes causes slight losses of torque, but in a turbo car you have plenty of torque, and the turbo itself creates an amount of backpressure (and to an extent even acts like a muffler in many ways). safe bet your car will get faster without cats, but there are other issues you'll have to deal with, like smell, noise, legality, and the possibility of setting off carbon monoxide detectors, if you have them.

[shemeld_135]

Originally Posted by bmw13

Option #1) removing only the secondary cats

Option #2)fully catless

Option #3)Stock

My car is stock and most likely will stay stock. Would option #1 or #2 benefit the car in any way? - or is it simply a noise increase. I feel like the car is set up a certain way and I am afraid to upset that. But if I can go a little louder while staying stock for the most part, and only benefit the car from doing so, I am all for it! So if any of you engineer-type-people want to enlighten me feel free, PLEASE

Will going this route to go louder affect the overall performance? I will not sacrifice performance for sound... But if performance can only benefit, the louder exhaust in return is just a plus! Any help/ enlightenment is much appreciated!

you can get a nice increase in HP by replacing your stock dp with a catless dp..i recently got a catless dp and added it to my jb4 and WOWWW it was faster ..also it didnt make it much louder with my berk sport axel back exhaust..not saying u cant hear it...but not as loud as i though it was going to sound

[bmw13]

I have read going catless with out a tune does hurt the car. It is a no brainer if I had a tune I would have had the secondaries off by now, but because I am not going to tune this car at all I feel like I could hurt the car more so than help it...

[AchtungF80]

Throttle response will be much more crisper and the car will be faster, but the downside is noise, smell and your car will sound like a $5k hooptie.

By the way....sound is subjective to the person but that's my take on it.

[1speedbike]

Removing the secondary cats will likely net you 5 hp. Removing the primary cats on a stock 1M will likely net you 15-20 hp. This is all without a tune increasing the boost, and thus the amount of air going through there. With a tune, this gain will rise. No bakpressure needed for these turbo motors.

[bmw13]

I am highly considering a secondary cat removal now... It really wont affect the torque though?!?

[Simsims]

save the planet some.

[1speedbike]

Originally Posted by bmw13

I am highly considering a secondary cat removal now... It really wont affect the torque though?!?

It will not. It's a common misconception that our engines "require" backpressure in the exhaust. They do not. These turbos are trying to shoot out as much hot air as possible, and in order to do so most effectively, they need the most free-flowing pipes possible. People who switch to AR Design 3" downpipes see pretty big power gains. Making the midpipes more free-flowing has the same effect, just diminished since the air is already cooling down and contracting by the time it reaches that area, and aftermarket midpipes are generally restricted to the stock 2.5" because all the connectors are 2.5" so that restriction is already built in.

For more proof, see this thread:

http://www.1addicts.com/forums/showthread.php?t=566495