I ordered the fmf fatty for pred 90 on jan 24th from parts direct , I called yesterday and Nate said fmf was delaying it's 2nd release until March 11th, they have many orders to fill so long wait if you get one, in the meantime I have put on the Hetrick pipe on my other sons pred 90, I can't wait to compare them both, but that might be like apples and oranges.
One thing I heard no modifications are needed for the fmf, where as I had to remove the battery box and oil tank for the hetrick.