I just this weekend made my own "race pipe" by removing my 2nd cats and resonator (e90) but left the stock mufflers. It was the most god awful sound I've ever heard. I installed a set of magnaflow mufflers two days later because I could not stand how raspy the car sounded. I would not recommend the race pipe unless you change mufflers too.
I was following an early 90's Honda Accord with a blown muffler and I couldn't believe how similar my car sounded to that. I felt so much shame!