[SS2camaro]

Thank you for taking the time to read this message and any help would be a big appreciated!!

I have a bone stock 2015 2SS Camaro with 2000 miles, I recently had a Legato axle back exhaust sytem installed. From the minute it came off rack at shop I've noticed sluggish idle response in the low rpm range (during cornering and trying to get back on gas) and sometimes a ruff idle. Before the install I never had these issues car always responded soon as I pressed accelerator. My question is this a normal? My friend has same car stock also other than he went with competitor sytem and I drove it and he didn't have any delay. Long story short I contacted legato customer support to see what they thought. They said its not there exhaust and asked if I deleted any other parts (which I did not) , I had professional muffler shop put it on per Legato instructions. While waiting for response from customer service I took car to dealership since it's under warranty they did full check on car and was told car was perfect. They did test drive vehicle and suggested I put back on my factory mufflers was told I either have a defective sytem or its not made for my car. I do not want to put factory system back on this vehicle after cutting it out can someone please suggest what they think issue is please. I did buy a K/n cold air intake but I have yet to put it on before I figure this issue out.