Vz v8 exhaust noise??!!

[Leevers]

Hey guys, I have a VZ SS Thunder and have recently had a full exhaust system installed and have a really weird noise coming from the cat converter area. I have NO idea what the noise is, but i've had the mechanic that installed it tell me it is normal, but I don't believe it. It is not an exhaust leak either. (had it on the hoist)

Exhaust specs:
Pacemaker 4 into 1 ceramic coated extractors (Not sure on size but I am told you can't get any bigger)
200ci cats
2.5inch Twin Manta Cat Back

I have a video also below in the link. The noise is everytime I remove my foot from the accelerator. Filmed with a gopro, so not the best sound. Much louder in person.
WHAT IS THIS SOUND?! - YouTube

Honestly, any help would be appreciated as I currently hate my car purely because of this noise..
System is now over a month old, so definitely run in, also since had the car tuned as well.

From the multiple posts i've read over this forum, I've noticed Not An Abba Fan is quite cluey with exhausts and manta systems, so if ya reading this, I would love for your input!
Cheers in advanced guys!

 

[Not_An_Abba_Fan]

That noise is sometimes caused by the mismatch in size from the extractors to the cats. If you have the 1 7/8" primary extractors, they will have a 3" outlet, the cat pipes are 2 1/2". If your exhaust fitter has a set of 3" cats he can bolt up to try, do that and see if the noise goes away.

Also, it sounds like you have the system with front mufflers, I rarely use that system, I use the hotdog front, sounds way better and you don't get that noise either.

 

[Leevers]

That noise is sometimes caused by the mismatch in size from the extractors to the cats. If you have the 1 7/8" primary extractors, they will have a 3" outlet, the cat pipes are 2 1/2". If your exhaust fitter has a set of 3" cats he can bolt up to try, do that and see if the noise goes away.

Also, it sounds like you have the system with front mufflers, I rarely use that system, I use the hotdog front, sounds way better and you don't get that noise either.[/QUOT

Thankyou thankyou thankyou! I will get some hot dogs put asap at the front as yes, I do have the front mufflers.. And I will also get the cats switched out for some 3 inch ones..

Was driving me insane as to why my v8 commodore is the only one i've heard with this sound!

 

[Leevers]

Can you recommend any specific hot dogs, and cats to suit this system?
And from what I've gathered over time, I am under the assumption you distribute Manta systems? If so, I'd be interested in dealing with you rather than the donkeys here in Perth