MOPED ARMY

My first expansion pipe was the biturbo. It was dog until 20 mph, and then it slammed in and i was at 35 in seconds. I have the GP and I don't think it opens up like the biturbo did, but the power band is much lower with the gp, but I feel it provides a better overall acceleration through the power band. Just my opinion. Oh, I ran the biturbo on the stock cylinder and a metra 65. the gp I only ran on the metra. Hope that helps!