Magnum
Well looking in my diary I bought the Mag from U.K on my last visit home, 18 months ago..so she's doing well!!
To answer the question, yes after the first few flights I added about 5g I think ?? to the opposite wing tip as the pipe, just cut a slot and epoxied it in.
As for the skid plate this has proved a great success for me, the sand out here in Dubai is hard when we have wet and rolled it, so the conventianal planes can take off and land.It's more like landing on tarmac than sand, although a bad landing can fill the carb nicely with sand!!!
Here a few pics