I'm trying to decide whether the extra flow is worth another $100. I can get a 40 series with 1 in/2 out with stainless tips for $300, but I could do a 50 series with 2 in/2 out with the same tips for $400. Is the extra flow of 2 pipes in the muffler going to make that much of a difference in power?? I hate to sacrafice the more aggressive 40 series for just a hair more flow. All pipes will be 2.5", or whatever the stock size is. Any ideas??
Here's a diagram drawn on a sophisticated drafting program...

 

if this is for a V6, do neither of these setups and get a single in/ single out muffler with 2.5 inch pipes. And if this is for a V8 DO NOT get the send setup unless you got a sooped up engine with lots of power. Most likely with both setups you have listed you will loose low end grunt(torque) with a V8 and no doubt in my mind you fall flat on your face performance wise if this was for a V6. thats my .02

 

forgot to mention these are for an '01 5.4L. I've read up about the torque loss, and I believe that if i keep just the single inlet 40 with whatever size pipe is already there, then it should give enough restriction to not radically change my torque. I'm contacting flowmaster and requesting some dyno sheets for various setups. After 50 views and only 1 reply, I suppose I need to look elsewhere

 

Use the Search feature. Here's what I found searching on SIDO

Other searches may also provide you with more info.

Dave