That's a lot of power decrease... 1000-1500 rpm is what you gain in the best cases when you use a tuned pipe, or a "special" muffler....

I use an exhaust deflector on my Magnum 46 xls, I got about 12500 rpm max, as soon as I can test I will tell you if there is any gain by removing the deflector...

Such decrease in power looks more than is with the baffle tan with the deflector....lots of rpms indeed..


Jorge