mirwin,
Take a look at the cowl binders on PSP Manufacturings website www.pspmfg.com. I have these installed on several of my models. They are easy to install, will not come loose and the holes in the cowl will never elongate. A friend told me about them a couple of years ago and I have used them ever since. When the guys at our club first observed how well they looked and worked they started buying them too. I think they can also be painted to match your cowl, but have never had the need to do that. If that is a concern ask PSP just to be sure.