Perrin 2.5 experience

[why?]

low end torque on a na car is 100% about back pressure. This is the exact opposite of what you want for high end performance. Down at 2000 rpm or so the car makes very little actual torque, so every little bit helps. The second you increase pipe diameter of any part of the exhaust the low end torque will suffer.

As was said though, just rev it a little higher and it will be fine.

[Leland]

Originally Posted by why?

low end torque on a na car is 100% about back pressure. This is the exact opposite of what you want for high end performance. Down at 2000 rpm or so the car makes very little actual torque, so every little bit helps. The second you increase pipe diameter of any part of the exhaust the low end torque will suffer.

As was said though, just rev it a little higher and it will be fine.

As the flanges were not originally level and therefore not sealing properly, a leak could really compromise back pressure. I leveled them but found that I needed to re-level the flange on the muffler section. I think I ran out of patience as it is a really tedious job. I'm curious to reinstall the Perrin and see how it compares with the stock unit. This whole thing started in response to the sound from the Perrin not being consistent and that the V band clamps needed periodic re tightening. That is when I found out that the flanges were not level. The one on the muffler most of all.

[Xxyion]

Originally Posted by Leland

As the flanges were not originally level and therefore not sealing properly, a leak could really compromise back pressure. I leveled them but found that I needed to re-level the flange on the muffler section. I think I ran out of patience as it is a really tedious job. I'm curious to reinstall the Perrin and see how it compares with the stock unit. This whole thing started in response to the sound from the Perrin not being consistent and that the V band clamps needed periodic re tightening. That is when I found out that the flanges were not level. The one on the muffler most of all.

So i just installed my Perrin this weekend. I made sure to try and drive it exactly how i was driving the car with the stock exhaust on.

I'm almost 100% positive that what you (and i) was experiencing was all in our heads. The Perrin has a slight more airy tone to it. You can hear a little bit more air being pushed out when you step on the throttle. Overall though other than that the car seems to drive exactly the same.

[Leland]

Originally Posted by Xxyion

So i just installed my Perrin this weekend. I made sure to try and drive it exactly how i was driving the car with the stock exhaust on.

I'm almost 100% positive that what you (and i) was experiencing was all in our heads. The Perrin has a slight more airy tone to it. You can hear a little bit more air being pushed out when you step on the throttle. Overall though other than that the car seems to drive exactly the same.

I did a before and after Perrin dyno over the last week and it definitely gained power. Around 6 hp and up to 8lb. ft. of torque reasonably evenly across the curve. I think part of what I was experiencing was that the Perrin flanges were not level, particularly at the exhaust section and so it was leaking no matter how carefully I installed it. Now that I resurfaced the flanges and it is not leaking,it is better on all fronts. The sound quality is quieter, consistent and does not drone on the interstate around 2.5-3k and the low end torque is improved.

[dtrop]

Just a comment about noise......

I have the same exact setup.

I drive with my backseats down 100% of the time. It's way more enjoyable to hear both the header and exhaust than with the seats up.

With the seats up, it's well, kind of quiet.

[Leland]

[QUOTE=dtrop;2981468]Just a comment about noise......

I have the same exact setup.

I drive with my backseats down 100% of the time. It's way more enjoyable to hear both the header and exhaust than with the seats up.

With the seats up, it's well, kind of quiet.[/QUOT

I am generally okay with quiet but I will have to try with the seats down for curiosity sake.

[nullredvector]

Originally Posted by Leland

I did a before and after Perrin dyno over the last week and it definitely gained power. Around 6 hp and up to 8lb. ft. of torque reasonably evenly across the curve. I think part of what I was experiencing was that the Perrin flanges were not level, particularly at the exhaust section and so it was leaking no matter how carefully I installed it. Now that I resurfaced the flanges and it is not leaking,it is better on all fronts. The sound quality is quieter, consistent and does not drone on the interstate around 2.5-3k and the low end torque is improved.

I am having the same issue with the 2.5-3k drone. Can you detail how you resurfaced the flanges? Was it just trial and error until the drone went away? I needed to use to double gaskets on the mid pipe to get a good connection and to stop it leaking.

How did you test for leaks, soapy water? Did you blimp the throttle?

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[aKaGorganZola]

+1 for the seat down gang. ��

[RickBH]

I have the 2.5 resonated Perrin and have found a fairly loud resonance around 2700 rpm. It is mostly noticeable under acceleration but is always there. The better Subaru hangers that have been discussed on another post helped somewhat but did not eliminate it.
I wanted to hear the exhaust but did not want the annoying drone. I have the auto so it is more difficult to adjust the running rpm but the sound from the exhaust when cruising on the highway is fine.
I have installed a couple of small lined muffler sections inside the muffler outlets and have added a little sound barrier layer to the trunk. It now sounds the way i like.
After reading this post I will check the connections to see if there are any leaks that would contribute to the noise.

[jflogerzi]

Also check out the thread for the exhaust hangers that come with the STI axle back exhaust that really help drone

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