Right now I got a flowmaster 40 series sido and it just aint loud enough. Would tkaing off the muffler and puttin a y-pipe back in its place work to make it straights?

 

it will work, but it may not be as loud as the flowmaster. I've heard people say that straight pipes sometimes isn't as loud as they though and it's louder with a loud muffler.

 

You don't say what you're putting it on, but I can tell you from personal experience that putting in a Y pipe with straight pipe is plenty loud on an original 4.6.

 

I just put singal into duel without a muffler on my 03 150 with a 5.4 and it is quieter than a lot of people would think a nice deep sound with on drone in the cab i think it sounds good .But if you want loud i would get hiflow cats and no muffler. The 03s have 4 cats so maybe if you got rid of 2 of them it might be loud.