The quick one word answer to this is no. But if you use one of the spreader exhaust resonator tips then you may be able to pick up a little bit of power, however what you will pick up is a great sound from your exhaust system. If the resonator or resonators or your exhaust system are restrictive, they will increase the back pressure in your car’s exhaust and that is where you will achieve your biggest gains in exhaust. The tips are more decorative than anything else, although when you shine them up they do look great.
For more info, see How Exhaust Radiators Get Rid of Rasp