Can I expect to receive similar results of a 4" exhaust by replacing the stock muffler with after-market but on a smaller scale? Normal 4" results of interest being (in order)...


1. Lower EGTs


2. Sound Quality


3. Quicker turbo spool


4. Very little if any MPG / Power gains


From my sig you can tell I not seeking the most extreme performance setup, just an improvement. I have been considering an Aero-Turbine or Flowmaster... or any other suggestions. If you have any advice, I would appreciate any information on the 4 aspects above. Also, what is your opinion regarding a 3.5" or 4" muffler on stock 3.5" exhaust?

bub_breeding,


You basically have all the advantages listed, better spool up, lower EGT's, better potential MPG, great sound of a diesel, HP and torque gains. The results will be smaller than if you add a full 4 inch system, you will alos have to rig up a muffler to fit correctly, be sure you use a straight thru design, not a baffled muffler.


We sell systems to folks like you every day, they have spent the time money and effort to install a muffler and then later go and change the whole system. My caustion to you is be sure you want to go this way as the cost of a muffler an installation is 100.00-150.00, a complete aluminized system is approx 350.00. So the effort and cost vs a bolt on system that does more for spool up , egt, HP etc for most folks is a better way to go with less headaches etc.


Mark @ DPPI

I almost changed out the muffler rather than buying a whole 4" system. Cost done locally with a quality straight through design muffler guaranteed to be quiet (or shop would replace) was about $110, or slightly less than 1/3 cost of MBRP aluminized (don't forget, you also have to add on the cost of frt to you). There are several trucks locally that have done this and they are all very happy with the results with improved mpg and faster spoolup. I went ahead and bought the 4" aluminized MBRP as it was supposed to be as quiet as the factory, which it is. Turbo spoolup seems slightly better (my 05 is the worlds slowest dog so it is hard to tell), too soon to tell if mpg will improve, and I have no way to tell about exhaust gasses. I though my 4" aluminized was poor quality when shipped, looked as though it had been installed, and is a very poor fit. I probably will canabalize it for the muffler and install it on my stock 3.5 system, which is a lot better quality and fit than the 4" system I was sent. I have seen the 305 stainless system and it was a much better fit and quality, but not worth the $ when one trades every 2 years and lives in a dry climate.

Chop the muffler and go with straight pipe. if you dont like the sound add a muffler. JMO Exhaust is very subjective.....whats music to someones ears sounds like crap to the next guy.

gardnerteam,


Wow sorry to hear that you weren't happy with the aluminized system, don't even know if you purchased it from us or not but the aluminized, T-409 and T-304 are built exactly the same. I mean you can interchange parts for all three systems and it will bolt right on.


If the system had been installed it should have had clamp creases at each slip joint, did it have any marks? Otherwise I can't imagine it could have been installed, fill in the blanks for us. We sell 25-30 aluminized systems weekly and have never had this comment and want to know what happened and or your thoughts as to why it wasn't the same quality as the stainless systems etc.


Mark @ DPPI

I have also heard that by placing muffler closer to the down pipe (further foward) you will have less drone and a quieter tone. Is this true?

I replaced my stock muff with a flowmaster 53553. It is 3&1/2 in and out and has the right offset to replace the factory muffler. It has a deeper tone than stock, but not overly loud. It does get a bit louder when the pilot injection kicks off at 2500RPM's. I looked into adding flow's 3&1/2 resonator, but it will not fit ahead of the muffler....too close to the heat shield and cab floor.


Turbo-spool up is much improved and my MPG went up slightly. No lag like the stock setup. When Michigan's use of salt claims this one (aluminized steel) I will probably move up to a MBRP stainless 4" system.

Like fred G said.


I replaced the stock muffler only with the Flowmaster. Much cheaper and sounds great IMO. Unless you plan on beefing the tranny and going for 475 + hp, I would save my money. Now if you want an exaust for looks.......well it's your money. I don't think you will see a noticible performance gain with a stock or near stock truck by switching to a complete 4" exaust system. The Flowmaster muffler will handle the Hypertech chip and more. Edited by: gmccall