Finally found the source of my major exhaust leak today. My header had a 2 inch crack where the primaries join together. I could hear my car making the chugging sound for a while now but I figured it was the header/dp connection. Had a my muffler shop check it out today and he found the crack. It welded up luckily, hopefully it won't crack again. It is a Jason Smith header, he made only a dozen of them or so for the IRL guys back in the day. Car feels and sounds a lot better now, does a crack like that hurt performance at all? It feels like it did but it may just be my butt dyno telling me things.

 

not likly because your tuned and i assume your catless if so and you shut off your second 02 sensor nothing would tell your car your having a problem i had the same problem with my downpipe i am on stock and removed cat and i didnt have a tig welder so i just mig welded it and about 5 months latter it has a ton of little pin holes. but its fixed now sounds better but i dont think youll get hp loss or gain from fixing

maybe its the sound of going faster

 

I'm not catless, yes i'm tuned. The crack was near the front o2 sensor on my header. The thing I noticed is that I'm seeing a little over a pound more boost now that it is fixed.

 

Yes a crack in the exhaust will hurt performance and the tune. It'll play around with the afr's.

As you already noticed car will run better. We are having the same prob with one down here.

 

It will affect scavenging exhaust from that cylinder, which will lead to less fresh air in the cylinder, thus less power. Your butt dyno says otherwise because it's loud lol.