I have a Mongoose and its alright but getting a little tired now. I like the Magnex system and it fits better and is a little less noisey.
If i was going to buy another off the shelf system i would go for the blueflame for the price i can get them for. I had one on my old car and as has been said its the same as a mongoose except it has bolt flang. The reason they are the same is because Blueflame used to make all of Mongoose's systems.