KZ1000J-3 hard to get from high revs to idle

Hi! I'm trying to get my Kawasaki Z1000j-3 through the danish version of MOT. The guy thought it was to loud... I was running a Mac 4-1 exhaust. So i changed to a Marshall Deep Tone (just as loud as the Mac) but now it won't go from higher revs to idle. The carbs need adjustment but it was not this bad with the Mac exhaust. After idling and heating up the headers light up turn red. This is not good right ? I tried adjusting the mixture screws to a thicker mix and now it goes from high revs to 4000rpm, then to 3000rpm and then after some time to idle. I'm starting to think false air but why now after changing the exhaust ?
Any thoughts ?

Simon

Sounds like it is lean. Check for air leaks. Pipe change could need more fuel, but you had a 4 into 1 on it before so it shouldn't be that far off now I wouldn't think. Retarded timing will also make the pipes glow. Make sure your ignition advance assembly is working properly also.

Check your carburetor holders.

Sounds like you are running lean...

Are you running the stock air box or individual pod filters?

Try taping over the airbox intake or pods using some masking tape to restrict air flow and see if that helps...

Also I'd adjust the pilot air screws out...try 1/2...one full turn , then 1 1/2 turns out from the original stock settings and see if that helps...

Check for air leaks around the carb boots...I use a propane torch (not lite) placing the nozzle releasing the propane gas around the carb intake boots and air box area...if it revs higher you have a leak and are sucking air which would cause your bike to run lean...to fix you'll need to change the intake boots...

Hope that helps