Need Help!!!

I have a 1987 Turbo II and just put on a HKS downpipe and exhaust today and now under hard acceleration the car seems to sputter. It actually feels like a miss but it will do it 2-3 times before hitting 6K rpms or so. Can anyone give me any idea what this might be? Should I try replacing the plugs, wires, etc? Any help would be greatly appreciated... Thanks..

you are boosting too high. Your exhaust and downpipe have let the turbo spool up more quikley making you boost too high. On the 87 TurboII the wastegate is too small for the turbo therefore making it overboost, the boost sensor then tells the computer to cut the fuel, making your car sputter. You can get a Fuel cut Defender/eliminator and solve this problem. It is ther for a reason thugh. The stock fuel system is only good for up to about 10-11 psi. I would invest in a fuel pump and some injectors,

what he said, and then get a/f and boost controllers and gauges... knowing whats going on under there from inside the cockpit is much help

Thanks for the info. I already have an a/f and boost controller I was getting ready to have installed. I will try the upgraded injectors and pump and hopefully that will solve the problem. Thanks again for the info...

Once you start changing the injectors and boost level a bit wouldn't you need to tune the computer so the car will run decently or does the rx-7's ecu have a lot more automatic adjustment field compared to other cars ecu's.