As of now, I have SLP shorties, X pipe, no cats and dual Dynomax Bullets with turn-outs. I loved it at first and still enjoy it, but can't take it anymore. Too loud! I want tips but I also want true duals. I've seen guys with true duals before on here who have also had theirs extended out the back. The rattling/vibrations are just too much for me to handle now.

1) Will having true duals w/ tips out the back take away that horrible rattle/vibration? Isn't it mainly the turn-downs that are making that happen?

2) If I replace the bullets with Spintech's or Flowmaster 2 chambers, will the interior noise be reduced a good bit with tips extended out the back?

3) What other options do I have besides the Spintech's/Flowmaster 2 chambers? I don't want the Borla mufflers.

 

I can see you are probably deaf now from the bullets. I have a true dual setup on my ls1 and a lot of the sound comes from the position of the turndowns. I have mine set so that the exhaust almost comes straight out the muffler. When you turn it down to the pavement it amplifies the sound and makes it louder inside the car. I have single chamber flowmasters on my ls1 and I love them. I have heard them on an lt1 and it sounded superior to mine. I'll post a few pics up of mine to give you an idea. I go to school at Clemson by the way, how far are you from there?
my duals 2nd pic last pic

 

i have duals out the back with single chamber flowmasters, part# 430408 i think. outside the car is loud enough to get you in trouble but isnt much louder inside the car then regular catback systems. these mufflers give me a noticable hp inrease over bullits on the same system. there is a video of me reving the car to about 6500 rpm on texasfbody.com if you want to hear it.

 

I have true duals including cats w/flowmaster 2 ch. race muffs w/turndowns at a 45 degrees angle and they are loud. My motor is far from stock, but you cannot compare a LT1 to a LS1 in terms of this discussion. I definetly know that the motor girth and heads make a big diff in each muffler sound. Loud pipes save lives and scare Mustangs!!

 

I've also heard the single chamber flows (on a ls1 though) and they sounded great! I'm about to build mine and I'm leaning towards the borla xs's out the back of course. I only like my exhaust loud when I'm on it, and the borla's are only 80db at idle.