I'm looking to get my exhaust done soon on my 2007. I don't want to go too loud so I think most likely I'm having the shop use one of the larger Magnaflows, and I'm pretty sure I'm sticking with SI/SO with the tip exiting pretty close to the stock location and direction.

I'm just curious how much this crimp they crush into the stock intermediate pipe quiets the exhaust down....does it even quiet it down or is it more for reducing interior resonance? I don't want to underestimate how much louder the exhaust will be if I have them cut the pipe before it to get rid of it.

 

It would quiet it down minorly. Its restricting your flow path though, so is your stock Y pipe.

 

Yeah, I figured it can't have all that much effect on the sound of the exhaust. I always wondered, since climbing under there for the first oil change, what the heck it's for. I mean, I'm sure Ford spent many hours and many dollars in the decision to crush that 2" lenght of pipe down to 3/4 it's diameter for some reason. My friend's '05 Superduty 10-cylinder had the same crimp in its stock int. pipe.

This is about what I want...quiet enough to disappear into the background when crusing without having to crank the stereo, loud enough to make itself known when I get on the gas. I make lots of long highway trips so keeping the drone away is very important to me.
http://www.youtube.com/watch?v=CPtTfXEA0Lc

 

I would just guess its a sloppy bend, OEM is mandrel but its all done by machines.

The 22" body may suit you well for OEM sound inside with a modest deep tone outside, and a 100% direct flow muffler.

 

Not only does it reduce noise, it also restricts flow. Bends always do, especially crush/crinkle bends.

That's why I went with 3" pipe on my DIDO. It flows about as much as 2.5" mandrel bends but costs much less.

 

It's actually not a bend...the crimp is along the straight section of the int. pipe between the cat and muffler.

 

You are running a dual 3" exhaust into a DI/DO muffler.... How is the low end loss feeling?

 

Torque has actually increased compared to the SI/DO Roush exhaust that was replaced. It's so torquey I have troubles keeping the big tires planted and these are high performance 275 55 20 street tires on a Supercrew. I think the X-muffler has a lot to do with it.

But I'm supercharged so I'm not sure how it affects N/A motors. I would guess torque will drop a little and the high end will open up quite a bit.

 

Oh ok. I didn't realize you were supercharged. I thought you put 3" duals on a N/A engine, the engine would hate that and run pretty lean.