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I have a mpi Yamaha 190 kit on my 2015 viper. I built a straight pipe for it and I'm seeing it over rev on take off twice. Them it spikes 10 psi and drops to about 8 psi. So for now to make sure the ebc isn't messing up. I'm putting the stock muffler back on to test. Does any one have experience with this. I'm sure I will have to re-clutch. And it's easy to lower boost with the waste gate. Just looking for info on clutching or experience with a straight pipe. Does the loud mpi muffler cause the same thing? I am thinking a little back pressure might be helpful.