Originally Posted by blownstang

That I believe. SLP is a straight through muffler just like Borla and Magnaflow. Stock mufflers, Flowmaster, and Mac are chambered mufflers. A straight through muffler flows better and will show better gains than a chambered. People get chambered mufflers to have that muscle car sound, but they will only give you a few rwhp over stock. My buddies SS Camaro gained 20rwhp by going from a stock catback to SLP.