I'm thinking of replacing my exhaust system. From what I 've read hear. I'm thinking of the aluminized 4" system. Now's the question? To put the muffler on or order the elimination pipe. Being its a CA. truck does anyone know if this would be legal. My thought would be to run without till told other wise. The kit would have the muffler with it so I could add later. I've noticed a low mpg & a little lack of power. So I'm thinking maybe a plugged cat.

Any other thoughts?

 

CA is a strict state, I doubt if you could get away with that at IM time. I lived in AZ for a while and had two systems.....almost. I flanged the inlet and outlet to the cat and muffler combo, as well as the system pipe. For IM time I would bolt in the "legal" stuff, go pass the test, then crawl under and unbolt the cat/muffler section and bolt in the straight pipe. Worked every time.

4" straight to the rear can be a little raspy under heavy throttle. Some like it some don't. 5" is quite a bit mellower, or add only a resonator and you should be fine. It's all in personal taste, but the larger diameter, the mellower (less chatter) it will be.

 

I was wondering about installing a free flowing muffler like the gasser crowd. What about a big flow master or something like that?

 

I used the dynomax ultra flow on mine, 4" straight through design, it's small, easy to fit , I put on stacks so length was an issue. I was weary at first, I didn't want to lose my sound, after all that's half the fun of owning a CTD is sounding like a Peterbuilt but it sounds AWESOME. I love it. it's quieter at idle, it still has the rumble and the turbo whine but just at a lower level, but the minute you get in the coal it has a smooth deep rumble to it. No raspy sounds at all.

 

No emissions testing in CA. I have been running a 4" with no cat for about 3 years now.

If you're thinking of running without the muffler, even with the Diamond Eye staight through muffler I run it still sets car alarms off routinely.

 

So, I want a straight Through System, Should I just get the 5" with dual tailpipes to overcome that huge bend over the rear axle. Then mabye just go to a junkyard and find a Straight Through 5" muffler? I tried finding one in town, but most guys dont go over 3" for some reason. I have plenty of room for a muffler, I just dont want it to cause any backpressure at all.

 

I wouldnt think youd have any backpressure with a 5 inch .You probably wont find a 5 inch muffler at the junkyard unless they have semis or dumptrucks there ..probably be best to just order a made up 4 or 5 inch exhaust kit with a muffler included.

 

you don't need a muffler!

there are truck parts distributors in Canada that can get you a 5" muffler or resonator pretty cheap.

 

Well, The only thing I need for an exhaust system distributor is the 5" SS downpipe, and the 2 5" SS Tailpipes, and mabye a Splitter, the rest I am just going to have to custom make out of some SS band clamps and pipe to suit my muffler. I was thinking of just getting one off of a big truck.

 

you're not going to find a 5" downpipe... all of the 5" kits use a 4" downpipe. there really isn't a need for a 5" downpipe untill you go with twins.

MBRP sells a dual 5" stainless system, but it's $1300 US!!!!! and I'm pretty sure you lose the spare tire under the truck unless you've got a pretty serious lift kit. they offer a catback version that's "only" $800 US

I know you're worried about backpressure, but you gotta realize that unless you're pushing 575-600hp, the 4" will probably perform a little better... in the 300-500 range, it'll definately perform better. what happens is the exhaust velocity slows down going around those 5" bends and actually causes more backpressure than would occur in a 4" system!

now, that didn't stop me from putting 5" exhaust on my truck... I wanted the look and sound that you can only get from a sewer pipe exhaust. and it did everything I wanted it to!

with all that said, I gotta ask, why not just put some stacks on it? with you living up north and talking about dual stainless, it'll actually be the cheaper way to go. you can get all the stuff you need on your side of the border. probably around $500 US... including a 4" downpipe.

the BEST performance IMHO would be a 4" system into stacks... a hair under that would be a 4" system under the truck (due to a couple more bends)

if you want the look and sound of 5", go for it, but if you're doing this in the name of the best performance, you're doing it in vain.

Forrest

 

Well the main reason I was going to run 5 inch is because I heard if your running a straight pipe or straight through muffler that a 5 inch is a lot more mellow and not as raspy as a 4". Around where I am the Police dont really have any real crime so they like to give out 'unnecessary noise' tickets to me and my buddies. As for the stacks, the reason that I do not want to go that way is because I dont want to cut into my bed because it will cause alot more inconveniences than I need.
But anyways, for the system then I guess I will run a 4" downpipe, then open it up to 5" after that then into my 5" straight Through muffler, then split it into two 5" tail pipes. Does that sound good or is there anything there that I should change?

Also where would be the best place to get the SS down pipe, and the tail pipes, or should I just buy some pipe and get some one to mandrel bend it to what I want? Thanks for any info.

 

Really? I slept through fluid dynamics class lol. Enlighten me

 

the gasses are allowed to expand and cool and they slow down even more and then get backed up around the bends...

on the big end, it doesn't really hurt when everything's cookin' pretty good, but it'll be a little more soggy on the bottom end... so your overall powerband will be better w/ the 4". didn't stop me from going 5"

Forrest

 

I would agree that the larger area of the 5" exhaust would cause gasses to slow and thus be cooler by the time the reach a point in the system but I'm still not clear as to why that would increase the pressure at the point? Maybe related to the Bernoulli principle?

 

That would be news to the phyics world that I read.

Just put a 4" pipe with a flow trough muffler. I bought a Flow Master 4" kit after my stock muffler gave out. Not a problem to install and performance and sound is great. If you want the 5" look put on a 5" tail pipe extender tip.