actually that alone will make a Corsa sport sound like complete ***. Will RASP horribly and become obnoxiously loud.
Will have to add in a bullet or loudmouth or some sort of resonator in order to make it sound decent again.

 

Very true! I added a 4x9x18 oval magnaflow in front of the corsa to tame it back down. I'm running pacesetter LT's and ORY.

 

This video is corsa sport catback with stock manifolds and cats in place. Weep hole is placed to the outlet facing down.

Silverado 5.3 corsa sport - YouTube

 

Yeah, I've seen that video before - sounds pretty good. I wish mine sounded like that. Hopefully sometime this week I can make a video so you guys will hear exactly what I'm talking about.

 

I'd just have to see a video of it. I have a corsa Db and it sounded like a boat when I first got my cam on stock manifolds. It sounded much better after Long tubes though.

You may possibly have the muffler on backwards like others said. Is it running on 7 cylinders by chance?

 

Just spitballing here, but are the corsa mufflers designed for the indiviudual engines? IE the mufflers for the 6.0 and 5.3/4.8 different sizes? If so, are you sure the muffler you bought, is the right one for your engine size?

That might not even be an issue but something to think about.

 

I believe the weephole should be on the outlet side

 

I think all my cylinders are good. Compression is good. Its noticeable when I unplug each coil with the engine running. Maybe I have a problem with an exhaust lobe or lifter.

The muffler came off an 07 tahoe, guy said it was too quiet for him so he put on a borla racing.

 

When I installed my corsa sport muffler as everyone has said (weep hole down, on exit side) my truck did not sound like all the ones on YouTube either.Truck had 111k on it and ran like a champ (sideband tuned 21 mpg on hwy) before the exhaust mods . I had the muffler shop raise the truck and cut the cats off. That fixed the sound issues (now it sounded like a corsa sport). 2 weeks later Went to long tubes and a mandrel bent off road Y and love it. Cats were my problem!

 

Yeah, I need to keep my cats here in Cali.

I think I have a fuel system issue. My pressure doesn't go any higher than 47-48 psi with the truck running. If I unhook the vacuum line to the regulator the pressure bumps up to 58psi. Revving it in neutral the truck sounds noticeably stronger with the extra pressure.

Also if I prime the system and let it sit for 10 minutes (per the GM manual) It goes from 55psi down to 48psi. I think remember reading that means the fuel pump check valve isn't working properly. So... I think part of this is fuel related but I need to do more diagnosing before throwing parts at this thing.