Got these "fender bolts" at a fraction of the price of aluminum fender bolts. (Use the aluminum fender washer if using for areas where higher strength is needed or u got a deep pockets ;).
The washer is manufactured by pressing out of the metal sheet, so it is hollow at the back. Which is good as it acts as a spring washer. But not advisable to use it for area where high strength is needed.
|PasswordJDM Fender Bolts vs Cheap Ass 'Fender' bolts|
Nope, this will not add more hp to your engine!!
I would replace all the washers with the aluminum type if I had the cash to do so ;p