See post #18 above.

 

Ronn, are you running a tune? Have you retuned for the DP and exhaust?

I'm running GMS1... I just picked up my Hahn Catted DP and then I got the Agency Power Cat-back at a really good price through them direct, yesterday ($320). These results are making me nervous... I'd rather have power, than a loud noise maker.

Subd for results w/o silencer

 

Here it is..had it done today. The DARK BLUE line are the results W/O Silencer. The RED LINE is from the previous dyno WITH the silencer. It's the same line in the previous chart. That chart also had a BLUE line, which was left out of this one and was almost identical to this RED line. For some reason, they included the same GREEN line from the previous chart, which were the worst results with silencer in.

W/O SILENCER=BLUE
W/Silencer= RED (and green too..over heated engine)

WITH and W/O SILENCER


Comments..substantial diff in TORQUE curve peak (+20 HP over W/Silencer). This chart doesn't show peak HP W/O silencer, that was in the previous chart (BLUE LINE) and was 299.2. So peak HP change was actually almost 5 HP vs W/O Silencer.

OK..what about the ORIGINAL #s..before the DP and Cat Back exhaust?

Here's THAT chart again:
BEFORE DP and CATBACK


COMPARISON WITH & W/O DP&CATBACK (no silencer)
RED LINE DRAWN IS PRIOR TO MODS
BLUE IS WITH MODS
( Thin red and green are with silencer)




Comments:
With the DP and Cat Back I gained a max OF 40 FT LBS AT 2500 rpm..300 vs 340! Peak torque difference was 20 Ft Lbs with exhaust mods (380 vs 360) . Most of the gain in Torque (and HP) was on the LOWER END, between 2000-3200 RPM. There was a slight gain from 4000-5000 RPM as well. From 5500 RPM up there was little difference. However, peak HP was sighly less (5HP) with the exhaust mods. This was because of the very slight loss (compared to stock exhaust) between 5500 and 5800.

 

You need to have tune for DP to work it's full potential. I already had HP Tune, so no need to retune. Don't need it for Catback though.

 

New silencer installed. This is almost 2" as opposed to 1 1/2" on original above. So that't 70% more flow area. It also has *slots* which are adjustable. I have them wide open for Max flow. Sound is very good with no drone at all on light throttle. This is probably the highest flowing silencer available for this application. The center tube is only 1/2" smaller than the pipe exiting the muffler itself (2 1/2") and there are additional flow slots as well.

 

do I see grooves on the passenger rear inner side of the rotor in OP? Might be imagining things.

 

What pic is that (reference the post #)? My rears have never given me a problem. There are very minor grooves, but ya can't see em here

 

Looks like the caliper casting flash groove to me. I took the burr off my rear calipers with a die grinder two years ago. When you corner, it causes a spot on the caliper to rub the rotor.

 

That's not my car...it was the Modern Performance Pic of their CB. I was showing how the pipe isn't straight, but *dog legged* to the side.

 

OK, not you then. NP.

 

yea im guessing the mpx exhaust has that bent so the 3" piping doesnt hit against the shield under the springs when going over bumps. i had that problem with my last exhaust, but my agency power doesn't hit that either so im happy.

 

That's the most ricer ronn looking silencer ever. The exhaust is not even centered either

 

That bend is significant and prolly slows flow down MORE than smaller Agency unit. Not a good design at all.

 

It's known as PARALLAX...angle of camera.
Here's another look...



The CUT OUT in the bumper isn't symetrical either...it has more space on the right side.


As far as *ricer*..doesn't bother me at all. Makes a big difference on *driver* comfort with drone supression. Might paint it black like the other one.

 

I just picked my Car up with the AP exhaust and the Hahn Catted DP. I love it. Its a tad louder than stock, but nothing you couldn't easily get used too. If it was any quieter it would be stock. The only real annoyance is when you are sitting in stop and go traffic with cars next to you. It screams "Hey, I am here, listen to me shift!" because 1st gear is so short. When cruising at 45-50mph, you can't even hear it with the windows down. The gurgles and pops when you let off the gas sound amazing.

 

Glad you like it..has a very nice sound for sure. I just didn't like the mild drone at cruising speed when under mild load (boost gauge reads under 10 Vacuum) and went with newer the silencer shown above. Still has a very aggressive sound, just more to my taste.

 

Ronn- around 2000 RPMs can you hear it rubbing/ bouncing around in the back where the muffler attaches? I also noticed it hangs ridiculously low where it clamps up under the driver seat. I know the stock exhaust hung a little, but this seems like if I went over a small speed bump it would drag... I know when I got it home from Vivid racing, the muffler had already popped off the hanger and I had to put it back up...

 

I have had no problems at all with muffler hanging low or moving at all. Are you lowered a lot? I have Pedders which only lower the rear 3/4 ". There is one clamp towards the REAR (not driver seat area?) which is over the slip fit. The pipe does sit a bit lower there..maybe 1"..with a space between the pipe and body, but not low enough to cause any problems. The bolts on the clamp are a 4" or so off the ground, but the car doesn't bottom in that area...as it would say, under the muffler.

Here is a pic of that area:





MUFFLER ATTATCHMENT
As you can see, it's securely attatched to the hanger and won't slip off it. Plenty of room to spare with ground clearance too.

 

I'm at Vivid now, hopefully they can fix it. It was hanging low since it popped of the hanger where the muffler actually attaches in the rear. I put it back up myself, but at low RPMs and when I let off the throttle after a hard excelleration, I can hear it rattle when I have the windows closed. The Tech told me it's cause there's a washer that needs to be bent/shaved and they know it's a problem on early TC's. (mine was built in Oct 2008). Funny story: when I was dropping the car off, the service writer grabbed a tech that was working on a lamborgini to work on my car. His response: "why are we putting an exhaust on a Cobalt?! I'm not done with the Lambo" service writer tells him to stop fooling around on the "Lambo" and get workin on my car. Of course I over hear all of this. So when I pick up the car, the tech says to me "when did these come turbocharged?" so I tell him...his response "holy **** man, those things are fast! I got on it in second and I nearly **** my pants. Wasn't expecting it at all". "Lambo" my a$$. I was a little mad that they didn't take their time with the install, but I didn't pay anything for it since I got a friend that works there to hook me up.

Edit/Side note: it's a $150k Car... Call the "Lambo" by it's full name.

 

The install is really a no brainer...I don't understand what went wrong. Show them the pics I posted here! Your set up should look like mine! There are other pics on this thread..so you can show those also. If they have a PC to log on the net...you can do that. If not print the pics and show them!

 

Reviving this old thread for another comparison to the MPX catback.
Here is a recent photo of the MPX. Note the kink and how close it is to the control box on top of the axle:
I don't think MPX is a good (smooth) design.



Agency:

 

I went with mpx since there store is down the street and I hate slip fit exhausts. Try driving a lowered TA I.ended up having my exhaust tacked is some areas and full beads in others and threw out all the clamps. I like the fix of.the mpx and the way it bolted together and had gaskets for a leak free setup. Also was easy as hell to.install and I have to say no drone or raspty which was suprizing. I was going to.get in on the turbo xs deal but again slip fit is a pita and never heard one. My only concerns when I buy a exhaust is fitment, quality, and sound. Looks only matter on the tip. I just wanted a deep tone and only loud when I mash the gas other than that at cruising speed like.on my way to.work i need to be able to talk on the phone when needed without asking managers to repeat themselves. Silcencer looks cool just too much of a pita for.me.

 

Silencer isn't really needed on Agency...I'm picky
Slip fit on this is a perfect fit with no problems whatsoever so far.
Glad MPX worked for you...I know it's a favorite here, but as you can see, it's not designed very well.