I'm going to modify an existing DNN installation and I'm trying to assign significant URLs to products through http module, look for etc

I don't find one way to assign an exact url to one product so I would like to execute a string replace to DNN output before the output is printed in HTML, so www.my-domain.com/default.aspx..... that represents one product is changed in www.my-domain.com/product/red-car.html.

Opening default.aspx shows me only <dnn:Form runat="server"...> tag, in which is execute (I guess) all data elaboration process.

How can I do to replace via ASP.NET output of that dnn:Form ?

Any help appreciated. Regards.