need muffler advice

about 10 months ago the mechanic at our shop replaced the exhaust and cut out the resonator and ran straight pipes on the company truck I drive. The truck was quiet before he did the work but after a week of ear aches I approached him to see if he could quiet the truck with either resonators or mufflers. At first he was irritated by my request, claiming that resonators didn't work, then he claimed that he thought he could find some 5" mufflers for the stacks, but quickly changed his story to "let me give my ears a chance to get used to the noise". It was clear at this point that he was simply putting off the work and had no intention of doing anything about it. I walked away and decided to do my own research on the issue. After about three hours of internet research I settled on a 5" resonator sold by FTE Diesel. It's about 3 feet long and fits the 5" exhaust on the bottom of the truck.

The resonator has a hole in the middle of it, half the exhaust runs through the middle of it while the other half runs through a two flute spiral. I installed it about four feet from the turbo, the flange out of the turbo elbows down to a two foot length of flexpipe and the resonator clamps to the flexpipe. A week ago there was a leak in the flange right up by the turbo, the flange was replaced although I still think there is a leak somewhere near the turbo but I can only hear it under a heavy load.

The engine is a C-15 Cat. What I'm wondering is if the resonator is causing too much heat or backpressure for the engine to handle, that flange that was replaced was put on new just a fews days before I installed the resonator. I understand there is some heat and torque and flex issues at the flange but I'm wondering if that flange should have lasted longer? Is that resonator compatable with the engine or is there going to be longterm damage as a result of installing this? I'm also thinking about replacing the straight pipe I cut with a length of new pipe, ordering a second resonator and placing one in each stack, therefore getting further away from the engine, reducing any backpressure by funneling the exhaust through 2 resonators after the "Y" instead of feeding all the exhaust through one resonator so close to the engine. I also understand from my reading that placing the resonator closer to the engine is more effective of deadening the sound? Would a resonator in each stack gain effectiveness or would there be more noise under the cab because of the change? There isn't room for a big 5' muffler under the middle of the truck, the present piping runs between the cab and frame of the tractor.

I didn't want to go behind the back and install this but the mechanic has already told other drivers after he straightpiped thier trucks that if they didn't like it to get thier own trucks. He has an attitude that he doesn't want anyone else turning any screws on the truck and doesn't like being helped by standarounds while he's working on the trucks. The owner works beside him, is rather easy to get along with but I figured if I approached the owner then he'd just talk to his mechanic and the issue would go nowhere.

If crap hits the fan where is DOT on cutting noise suppression out of trucks as he has done to a number of them already? I'm not much on whistleblowing but if I get fired out of this deal I'm probably going to talk to DOT about my rights as a driver. I feel this is totally cheap, lazy, and ignorant and considering that we drivers spend 50-60+ hours of the week listening to the truck that it totally lacks consideration. The mechanic drove the truck out of the shop and claimed it wasn't very loud at all but he never hooked up to 48,000 and took it up a hill to hear the rumble or jaked it on the downside to hear the loud "BAP-BAP-BAP" of the jake. He was simply trying to sell the idea that the truck wasn't loud and avoid the discussions he's already had with other drivers on the issue.

Could use some advice on this issue, need to know if this resonator will work on this motor, if there are issues with the flow rate and if I'd gain anything by going into the stacks with them, and also the DOT angle on this. I'm sure there are some drivers and mechanics better versed and more experienced than I am about this, I could use some sound advice and your thoughts on this issue. Thank you in advance!

 

thanks for your responses.....mechanic cut out the resonator from the original exhaust because it was one of those box types about a foot cubed, it wouldn't fit his plan of running the pipe in the six/seven inch gap between the frame and cab. That and he doesn't drive 50 to 60+ hours a week or listen to loud trucks drive through town so excessive and needless noise doesn't effect him. It's cheaper to run straight pipe and be ignorant.

And Charlie, I was thinking about doing the stack thing but now thinking differently since your experience wasn't as you expected it to be. Thanks for your input also.