I ordered an Ofna box from Tower Hobbies and it pretty much sucked. I could not get the pins to align the car and the spring mechanism required a lot of force to push down and engage. The wheel was also too big to properly engage the losi engine. I did not feel like hogging out the chassis so I opted for the red/purple Mugen box for about a $100 and that worked for me. Somewhere on here is a picture of a guys setup with the Mugen box and I followed the picture with success. There were no modifications necessary to the box or car with this setup. I think the box is a Mugen Pro B II or something. I will use the ofna box for my 4 tec or something.