[SYCARMS]

The reason to gut the muffler is to increase flow efficiency.The more air and fuel introduced you will need more exhaust flow. Take a funnel for instance. You have a funnel with say a 5" opening and reduces to a 1" opening. When you moderatly pour fluid everything flows well but increase the pouring rate the fluid soon starts to back up filling the funnel. If you than make the bottom of the funnel 2" the flow rate will increase. The point is to add fuel/ air you must increase exhaust flow as well. The best I found for a slightly modded engine, is to find a wood dowel to fit the exhaust tip tightly,for this serves as a pilot for the 1 1/4" hole saw to drill out the rear of the muffler. This will greatly increase the flow. I also insert a 1 1/4 pipe for the new exhaust tip and weld it in place of the old one.This will give you a nice mellow tone and also help in exiting the exhaust. Their has to be a certain amount of back flow in the exhaust for optimum performance. Rule of thumb is a ratio of 100% fuel air to 85% exhaust. So totally gutting the muffler or running with no muffler will hamper performance. I also recomend installing the larger tip as described previously to leaving a hole or even drilling of several holes. The exhaust should flow as freely as possible out the muffler which the tip provides. Hope this answered your question. TOM