What's going on with the performance of my Z
 

I need guys some help understanding what is happening to my Z. All of the sudden, my Z has drop very low in performance, so low that is almost disturbing. I don't have a clue, what is happening, all I can say is that the last modification I put on my Z was the "Resonated Test Pipes". After I did this my car was running great, real fast and very responsive but lately all that has changed.

I have an appointment this coming Monday with a dyno tuning shop here in SA, Texas to tried to tuned A/F and Ignition Timing on my car with the "Greddy eManage Blue". What is troublesome for me is that I don't understand, How a car can go from excellent to mediocre in performance. The car fills like is pulling a heavy trailer, I punch the gas and it takes my Z a long time to respond. Any comments are very welcome guys.

I would say lose the test pipes and put in some high flow cats or try the stock cats and see, before throwing more money at the problem.

That's the problem when playing around with souped up cars. Crap like this happens.

So what happened at the tuner?