What's the difference

[Advocate07]

What's the difference in HP/Tq gains when doing a full system exhaust vs. after market muffler and trail pipe..?

[sudden urge]

Just swapping the muffler usually nets about 1/2 the gain of a catback system.

[Blackbeauty]

Since CT links are not allowed on here, here's an excerpt from a post by Shailey regarding some exhaust configurations that he tested. Hope it helps.


First of all, if one of the mods finds this useful enough to make a sticky on it...great. If not that is fine too.

I have received quite a number of PM's lately asking about exhaust. I do not mind them, in fact I enjoy helping people out and answering their questions. If you have questions after this post, still feel free to ask them, I will answer.

I know that there are many peole on here who know more about exhausts than I do as far as the technical stuff. But, in the last two months I have done around 40 dynos with many different combinations of modifications and exhausts. The systems that I have had include the following now:

1) Full Stock set-up with 22" magnaflow muffler
2) Magnaflow Catback
3) Gibson swept side
4) Borla Dual
5) Flowmaster 40 series
6) Flowmaster 70 series
7) JBA single exit

I will provide what I observed during the whole process to try and help others determine what is best for their needs. When I mention drone, I am extremely sensitive to the frequency that exhaust emits. So your level of hearing may be different than mine.

1) The full stock set up with the 22" magnaflow provided great numbers. The hp and torque increase from stock was 8 and 14. Sound was a little louder than stock and there was noticeable drone to me at 58 to 62 mph. Bang for your buck can not be beat here. Once again I ONLY changed out the muffler.

2) Maganflow catback single exit provided the best gain period with the STOCK titan. The numbers on the website of 18 and 22 were factual peak to peak numbers. Not a play on numbers like many manufacturers do and show how much you gained at a certain rpm when you actually gained on 2 or 3 peak horsies. One odd thing that needs to be realized with this set up is it uses the STOCK Y-PIPE. I tried this set up with a custom 3 1/2" Y-pipe and lost a lot of torque. drone once again, is pretty noticeable at speeds mentioned above.

3) Gibson Swept Side is in my opinion a great all around exhaust for a couple of reasons. One it does provide medium gains in hp and torque. But two it has a great sound with almost no drone. It is louder than stock at WOT, but at start up it is just a deep tone that sounds great. But if you want something that is loud and mean, this is not for you.

4) Borla dual. It sounds really good to me. Cruising speeds had no drone, drone was only around 45 mph. the gains in hp were comparable to the gibson (12), but the toque gain was very minimal. But it is a very clean sounding exhaust that will please MANY and the finished look is very nice.

5) Flowmaster 40 series did not stay on for an entire day. Drone felt like my head was going to cave in. I greatly apologize for not being able to tolerate it to give a full evaluation, but the drone was heavy between 40 and 70 mph to me. And that is where I drive 90 percent of the time.

6) Flowmaster 70 series. Very good sound. Not to loud, drone was minimal around 1600 rpms. Provided nice hp gains that were equivalent to Gibosn and Borla, but once again the torque gain was very minimal. This exhaust at wot was definitely able to turn some heads with its volume and I did notice a couple of pops after going WOT and then letting completely off the gas. So it performs like the Gibson and Borla but has a little more agressive sound than both of them.

7) The JBA provided the best gains AFTER the header install. I do not have perforamnce numbers with the stock exhaust manifold, because I purchased this system AFTER headers. Previously the Magnaflow had the top gains hands down, but after the headers, this one etched out on top by 4 hp and 6 pounds of torque. I think that JBA did a good job matching their systems up. One thing that is interesting though is the muffler that came with it was a K & N muffler. The Y-pipe is smaller than ALL OTHER catback systems at 2.5"...EXCEPT where the bend in the tubing is and at the Y. The bend in the tubing on the drivers side expands to a little under 3" and then shrinks back down and it seems to act like a velocity channel. And the Y has two 2.5" pipes that come together to a 3" collector. There is some drone at 1600 rpms does not matter the speed, but it is definitely tolerable to me. This is a fairly loud agressive exhaust but is still not up with the Flowmasters or Bnaks.

So one conclusion that I was able to come to is that the 5.6 loves back pressure. That is where the low end torque comes from as does the max torque. It is funny that the 3 systems that produced the best numbers (hp and torque) used the smallest diameter Y-pipe and 2 of those were with the STOCK Y-PIPE and the other has the same diamter as the stock y-pipe. The dual systems lost speed in the lower range (below 40 mph) and I am convinced that is because of the minimal torque gains and I believe loss of back pressure. So if you want pure sound, the duals are the way to go. But if you want performance, the single exits with the smaller Y-pipe proved to be the best.

I will also be installing and dynoing the bassani system soon. I know that they are big into vette's, but I heard one on a friends Z06 and it had a great sound and provided pretty good gains on his vette.

Now please do not start writing in and bashing me because of my findings. All of this was done on the dyno and the on road findings were times with a Bel FX2 and my ears. Times can be affected by humidity, temperature and wind.

[Advocate07]

Thanks a lot guys.. my friend was curious since I had welded on his muffler