I think Stu's problem is not being able to read what appears to be the new type English language.
Stu, I think what our friend is trying to say is:
Just wondering, in your opinions should I keep my Mongoose 5" tail pipe or should I change it for a Hyper Medallion 4"
In my opinion if it's just looks your after you should bin you chav 5" tail pipe and either go for the 3" Mongoose tail pipe or your choice of the 4" Hyper Medallion.
Steve