mufflers or no mufflers??

Flow numbers for mufflers is one of the most useless specs out there. All of the performance mufflers flow more than anything but the biggest IHRA prostock mount motors can flow.

As others have stated it is much more important to have the right size pipes and lengths in front of the motor that what muffler is there.

Some time back I read an SAE paper on designing zero loss exhaust systems, that is the motor will make as much power with a full exhaust as it does with open headers.

The interesting thing I took away from that article was that it is easier to design a zero loss system with a chambered muffler than it is with a straight through absorbtion muffler like a magnaflow or ultra flow. The article stated that with the chambered muffler once the exhaust entered the muffler the rest of the system appeared to the engien as though it wasn't there and the the absorbtion type the rest of the exhaust past the muffler appeared as a restriction.