[fesler]

We use Competition all the time and love the way they fit, you have to cut out the tubs and if you are going to change your frame rails I would build my own set of tubs as you can go wider and make them cleaner. here is what we just did in our 69 Camaro

If you look in the 1st picture you can see where the stock frame rail was and we move the new rail over as far as we can to clear the larger tire and still fit the fuel tank. The rest kind of give you an idea of what it takes to put these in with the tubs and how it will look.

We can fit a 345 in the back with lots of room to clear and thats a wide tire on a 19-inch wheel. Hope this helps in some way