Originally Posted by URG8RB8
The Challenge Street made the car a bit more responsive. It pulls better than with the stock x-pipe. That stutter rocking when the car is still cold is not as pronounced, either. Others have commented on how cutting out the secondary cats is the same. I actually had that done when I had my OEM muffler mod. I lost some low-end torque with that setup, to the point where I had the secondary cats placed back on. If you want better performance gains, installing an x-pipe with either no cats or high-flow cats is the way to go (ex. Challenge SPORT) - not with just a secondary cat delete.
I went to the Corsa exhaust because my OEM mod began to rattle after a year or so. I didn't want to open the muffler back up to troubleshoot where the loose connection was, so I went aftermarket. I chose the Corsa, but it wasn't what I was used to. The OEM mod wasn't boomy at all, and it was very high-pitched and somewhat raspy (which I like). But the Corsa added some low-end bassy sound, and it wasn't as high-pitch as I was used to. It's a great exhaust, but I felt that it was missing something after about 5k RPM.
I installed the Challenge Street on my Corsa to see if the tone would change. I was not at all focused on the performance gains, which are minimal. The tone changed, alright. If you don't push the car, it sounds nearly the same as with the stock x-pipe - maybe a little louder. However, giving it some throttle turns it into a beast. The sound under throttle is higher pitched and ever-so-slightly raspy. I think the best part is the subtlety of the sound when exhaust braking, or letting off of the throttle and slowing. It gives a dynamic low rumble that's difficult to describe. Throttle blips are also fantastic. Instead of just engine revving, it projects a "WHAP" sound. I think it would sound incredible on a DCT car, but it is great with my 6MT.
I have also heard my friend's car with this x-pipe mated with the BMW Performance exhaust (a horrible combo!) and the stock muffler. The dynamic sounds are still there, even with the OEM muffler. Again, it's a little more responsive. And those throttle blips sound amazing. This is also a very good combo.
Thanks for the detailed response. I had a challenge street pipe paired with the eisenmann sport on my last m3 so I know exactly what you are describing. You confirmed what I was curious about, which was the corsa needs that 2nd cat delete in order to be heard above 5k. I'm surprised though about the description in tone. I thought it sounded high pitched in videos and from a few descriptions. Not a big fan of rasp but I do like a higher pitch vs bass.