I have a 2004 navigator with the 32v Intech motor, am looking to do a custom exhaust system (true dual) from the manifolds back eliminating the 4 cats and going down to 2 cats. I've done a system like this before on my 01 but wound up being a little too loud for me, I'm thinking it's largely because I used a Spintech muffler. My question is has anyone used a muffler that's pretty free flowing but still remains pretty quite?

I have a 2004 navigator with the 32v Intech motor, am looking to do a custom exhaust system (true dual) from the manifolds back eliminating the 4 cats and going down to 2 cats. I've done a system like this before on my 01 but wound up being a little too loud for me, I'm thinking it's largely because I used a Spintech muffler. My question is has anyone used a muffler that's pretty free flowing but still remains pretty quite?

I've been considering a similar system but I have come to the conclusion that a larger diameter pipe from the manifold exhaust pipes (Y pipe) back would be a better thought due to space restrictions, Then split the pipe near the rear end to have duals at the end. I'm going to look at the exhaust on a F 250 7.3 diesel PUT for comparison. Removing the cats will increase noise levels.

I found that the 32v motor is really restricted by the 4 cat system and tends to really "wake up" when it's taken down to a 2 cat system

This is in the future for my wife's car. please provide updates on what you ended up using. Going to do full header back exhaust and open intake.

If anyone is interested (still) deleting the two rear cats and installing a mandrel bend if your keeping a single exhaust is the way to go as well as deleting the rear resonator. this alone will boost up torque, HP,and MPG. Not to mention release a lot of back pressure issues!!!! GL