October 22, 2003

Need your help. I've decided to stick with Flowmaster when I install my catback. I know about the sound and the difference between the 40 and 50. But want to know which one would my truck benefit most from for performance purposes.

I'm going with a SIDO setup and here are the choices I've narrowed my search down to.
50series 2.5in/2.25out prt#525552
50series 3.0in/2.50out prt#530552
40series 2.5in/2.25out prt#9425400
40series 3.0in/2.25out prt#9430422
40series 3.0in/2.50out prt#9430402

Now I'm leaning more toward the 50 because I don't want to be obnoxiously loud but do want to wake up my 4.6L. I had the first one installed on my 4.2L and really liked the sound but would that setup on my 4.6L rob me of power because it may be too restrictive still? I also am impartial to keeping the stock pipe entering into the muffler as well instead of changing to a 3" pipe from the cats. Anyone running these mufflers in a SIDO setup can offer me some sound advice?