After my PI and ESS installed, car runs great. much more low end torque and engine rev up pretty nice. However, it still feels too robust and rather soul less... after few weeks, i finally decide to have the dealer replace it for me.
My biggest hope for this system is probably gain good sound from rev matching, i just love to hear those race car doing it on the track. but O man..... this is better then what i was hoping for, this thing is A M A Z I N G when i blip the throttle on freeway. Im sorry, i dunno how to put it in words, you just have to listen to it in person.
Full throttle is also fantastic, you can really hear a lot of detail and definition of the engine. I guess bmw deliberately dont want new customer to hear it in order to put shine on the 335i... they know damn well turbo charger destroy the exhaust sound quality.
I really feel like im driving a completely different car now, really dont care that much about performance gain from it. It turns my car into something special that i can enjoy everyday
Update: after a few days of driving, didn't notice too much difference in performance until last nite I drove it with two other guys on the car. There is definitely more torque, uphill it just keeps on pulling into high rpm. Especially when you drop down a gear or two on highway, the accelerator feels very light and smooth.
Similar to my PI, performance smoothed out and got better in a few days of driving.