[13screw]

This weekend I installed corsa's new double X with the extreme axleback. First I want to say the quality is amazing and everything fit perfect. This system deletes the secondary cats and is all 3" back to the mufflers. This system is loud, and has me considering switching to corsa sports as the ol lady thinks our neighbors are going to call the hoa. I leave the house at 4:30am on weekdays and startup is no joke with this setup. Other then that it's amazing, 0 drone at any speed, near silent on the freeway, can cruise around at stock like noise levels, but touch the throttle and it comes undone.
My only issue (other then the neighbors) is the car feels noticeably slower. The low end torque just doesn't feel the same. Is it me? Or have other felt this also.. iv heard these car will adjust for over temp cat protection, and dump fuel to cool the cats. I have no CEL but it doesn't feel the same on the hit.

Also, anyone looking for black corsa extremes or has sports and wants to switch pm me.

[Vtor_ZL1]

Noise =/ speed.. now that it's noisy all the time, you don't feel the "speed" as much.

[13screw]

I'd believe that but the car usually breaks loose at 50mph and below no issue. Now it just kinda feels lazy, idk.

[BMWM.D.]

Could there be any contact between the exhaust and any hard parts of the car (frame, transmission, etc.) ? I’ve seen that cause false knock and loss of power.

And man, I bet that thing is loud on cold start. No way my neighbors would tolerate me firing my car up at 4:30 am. With headers and stock muffler, mine is stupid loud on startup. I’ve considered changing the muffler, but I have an HOA to deal with too.

[Can'tHave2MuchHP]

Kind of impossible...If you think it out, the most you could be losing is dropping some back pressure which will increase peak HP but possibly lower torque on the hit/LOW RPMs. By dropping, I mean literally 5-10 RWTQ low end (not peak), certainly no more than 15. Even a set of 2" primary Headers that are dumped won't lose more than 20 RWTQ. The LT4 is such a nasty torque engine that it would really be impossible to say that you feel 5-10 RWTQ especially since the car is going to rev out the first 5 or so gears so fast you won't be able to measurably feel changes, at least I don't think so. You might want to check for other issues or see if you can actually measure a performance loss via 1/4 mile times/traps or see if you can get it on a dyno to see if it's putting out an exceptionally low number like 520 or something.

I run this setup (With a Borla X) and I love it. To me the noise makes the car feel even faster than it was before. Paired with an intake, I'm very happy with the performance of the car. It's definitely nasty loud on WOT. I don't dare get on it where there could be a LEO in hiding. Back roads and highway entrance ramp to max of 80 or so MPH. Anything over that and you're asking for it without great awareness. The cruising manners of this setup are unbeatable.

[13screw]

Well my new way is starting the car with the garage closed, putting it in reverse quickly so the rpm drops, then open the garage and sneak away. Lol.
Canthavetoomuch, i understand what your saying, but even from the first time driving it after the exhaust I was like hmm maybe I didn't get it in all the way. Then did it again and still noticed it.. I found this post and got me thinking and the rich condition as the op said his car went into car over temp protection immediately. I have the same mods tb/intake/exhaust

https://www.camaro6.com/forums/showt...php?p=10014721

[nicktechla]

Cars do feel faster when they are quieter i think

[ninetres]

Originally Posted by 13screw

Well my new way is starting the car with the garage closed, putting it in reverse quickly so the rpm drops, then open the garage and sneak away. Lol.
Canthavetoomuch, i understand what your saying, but even from the first time driving it after the exhaust I was like hmm maybe I didn't get it in all the way. Then did it again and still noticed it.. I found this post and got me thinking and the rich condition as the op said his car went into car over temp protection immediately. I have the same mods tb/intake/exhaust

https://www.camaro6.com/forums/showt...php?p=10014721

That was my car. It would seem to me like if it goes into cat over temp with the secondaries deleted.....it would go into that mode even easier with them there. Exhaust gasses heat up passing through the cats.

[13screw]

Hey So looking at your graph it appears that the stock pull in hotter temps was a smoother and fueling was consistent. Your pull in cooler temps with the mods looks like the car was adding fuel and power was dipping then gaining then dipping. Idk iv done a lot of research tonight and some ss owners have posted similar thoughts on loss of power/tq. I guess it's time for a tune and pulley lol

[BMWM.D.]

“Cat over temp” is simply a calculation in the ECU. It doesn’t have any way to actually measure the temperature, so removing cats should make zero difference. From
My experience, COT kicks in very easily on these cars. Though I really don’t think it’s noticeable seat of the pants. Maybe a little dip on a dyno chart.

What you may be feeling is throttle closure. I was getting it big time with just a Roto-Fab intake. It was fine heat soaked on the dyno (for a baseline), but on the street with cooler coolant and IAT2s, it was closing the throttle substantially. I can’t remember if it got worse when I put my headers on, as that’s when I started working on the tune.

[Stealth7]

I just added an intake and I can feel some difference in the low end but it appears to be more than made up for from the mid to upper rpm ranges. The car shifts more quickly and pulls harder. I am about ready to add the same type of exhaust indicated in this thread except using Borla S type. I suspect the feelings of the original poster are simply based on the better breathing of the car and that ultimately power is up a bit

[777Jackpot777]

I just installed Roto fab and MBRP cat back exhaust and I was going to post something similar to this because I kind of felt like a loss of power occurred but I think it may just be that it’s so much louder now at WOT it takes away from that feeling of how freakishly fast your accelerating.

[777Jackpot777]

Also the MBRP is a great all around exhaust and me and mechanic checked install 3 times but there’s a slight vibration for a split second when accelerating from a stop in first gear then immediately goes away. We are under the belief that the resonators on this system are poorly designed and are slightly touching and seem to be the culprit. Has anyone else experienced this with any aftermarket exhaust?

[BMWM.D.]

Originally Posted by 777Jackpot777

Also the MBRP is a great all around exhaust and me and mechanic checked install 3 times but there’s a slight vibration for a split second when accelerating from a stop in first gear then immediately goes away. We are under the belief that the resonators on this system are poorly designed and are slightly touching and seem to be the culprit. Has anyone else experienced this with any aftermarket exhaust?

This is why I mentioned possible false knock. I’ve heard of it happening to people from very minor exhaust modifications. The knock sensors on the gen V motors are very sensitive.