On my truck (HEMI) there are three mufflers visible. The first small one which I guess is housing the catalyst, then the second 40" long one, and then a third small one located at the very rear.
Will I increase the exhaust sound a lot by replacing the 40" muffler with a 3"straight stainless steel tube even if I leave the front and rear muffler as it is?
Are there any other technical side effects related to this?
Living in Europe I do not have access to all the aftermarket performance goodies that you guys do, so I figured this could be an alternative.......

 

You could straight pipe it. I know DMH Performance does ship their cutouts overseas if that helps.

 

You should have a two cats coming off the manifolds then possibly a forward resonator then the big can is the muffler and then another resonator and the final section of tail pipe sticking out. Removing any single component will increase the exhaust sound. Replacing the muffler with a straight pipe will make it pretty loud, but with the tail pipe remaining in place with the resonators it should sound good. And if that doesn't suit you, remove the resonators and replace the muffler. You have lots of combinations you can try. Good luck..

 

Thanks! Do I not have to worry about reduced resistance or any catalyst sensors being triggered?

 

only thing you would have to worry about is removing the cats. after the cats can be straight pipe if you want. with out the cats your 02 sensors will turn on the check engine light.

 

The two smaller "mufflers" one just before the actual muffler and the one after it are resonators, which are designed to aide the muffler in keeping the noise down. Simply removing the two resonators will add a good bit of "loud" back...

 

Well, I have an '08 that only came with one resonator and it was the one at the tailpipe after the muffler. Even with only one resonator and that giant muffler, my exhaust was pretty darn quiet. Removing both of your resonators isn't going to be near enough IMO. i would do as you stated and straight pipe the muffler and just keep the 2 resonators that the '06's have.
One thing nobody has mentioned or warned you about yet. You have MDS. removuing your muffler or resonators or any combination you can think of will resonate the exhaust pulses into the cab. Right now, you can't really tell when you are in MDS mode and when you are running on all 8cylinders, but with a catback, resonators removed and/or the muffler replaced or straight piped...You will definately hear and know when the MDS is active. It's a very distinct and annoying IMO fluttering sound. Sounds like a helicopter in water under your cab.
If you have a handheld tuner such as Diablo or Superchips, then you have the ability to disable the MDS feature and you will not experience this annoyance. Just beware though, your truck in no special case and neither are your ears. You will hear it and it may or may not annoy you, but 99/100 people it annoys. Just a heads up.

 

You obviously have some options. Just keep in mind the the resonators are there to knock down the droning you hear in the cab. I have owned differend 2nd gen Camaros' for more than 13 years with different exhaust setup's. I remember that even though I thought the exhaust was not that loud, it was annoying to drive my last Camaro when I had a headache or did not feel well because of the droning I felt while driving. The muffler I have on my Hemi is not as loud as the Camaro, but I kept the stock resonator on my truck, so the sound is much more enjoyable.

If you did a search and read many of the different threads on this forum about exhaust, you will find a good number of people that removed the resonator(s) at some point, and put them back on due to droning in the cab.

Maybe you should try just replacing the muffler with a piece of straight pipe, keep the resonators, and see what you think? That would be the cheapest way to start.