So we've all heard the myths around taking the silencer out, you will dyno more whp vs. with a silencer and also with a silencer, while you will dyno less whp you will dyno more wtq. Well, this isn't a dyno story but it is a vs story using my xb and a guy's xa.

All motor performance mods on xb:
- Aem Cai
- Dc sport header
- Jic exhaust
- Shorter throttle cable (just to get rid of slack, no whp/wtq gains)

All motor performance mods on xa:
- Injen intake
- Dc sport header
- hks exhaust

Now, before i go further i will say that each car should have about the same whp and similar wtq even though i have a cai and he has a sri. Also, both are automatics and both of us manually shifted with trac off and o.d off. All tests were 0-60, i do NOT recommend street racing, if you are interested in racing please go to a controlled track environment. If interested in Autocross or Road courses, IM me and i will help you with your set up and point you in the right direction. I can also inform you of rules and regulations if you need me to.

Controlled tests:
Both with silencers: I pulled from him off the line but once shifting into 2nd, he pulled away with an end result of beating me roughly 1-1 1/2 car lengths.
Both without silencers: Xa pulled slightly off the line, but catching up to him before 2nd and passing once into second with a final result of me beating him roughly 1 1/2 car lengths.

Given the result of the controlled testing we did, you can tell that we are fairly equal drivers and i could be putting slightly more whp than he is. While the xa is 100lbs lighter give or take, the cars are fairly even... As close as you are going to get.

Silencer vs. No silencer testing:
1st test, Xa no silencer Xb with: He took me off the line and pretty much pulled away the entire time, while in 2nd it appeared i was catching up to him the final result of this test was him beating me by roughly 2 car lengths.
2nd test, Xb no silencer Xa with: Similar as before with the replacement of the xa for the xb, i had pulled away from the line and remained pulling away the entire time. We had estimated that i had pulled close to 2 1/2 car lengths on him in the end.

End results:
Both Silencers: Xa win
Both Non: Xb win
Xa no Silencer: Xa win
Xb no silencer: Xb win

Dead even as far as wins, but the result was while with a silencer dyno's tend to show less whp, more wtq the extra wtq does not replace whp. In a light car like the xb/xa, it did not surprise me one bit that the results turned out the way they did. I was surprised that the both silencer test showed him winning and non-silencer test showed me winning. However, that could have been because i was shifting slightly higher than he was. After the testing i asked him where he was shifting at and he said he'd change gears right on redline, while i was shifting just after redline. However this is driver choice and he was just shifting where he felt comfortable with. While we aren't talking about a huge difference, it may very well be it has enough of a difference to change expected results.

 

wow, very interesting analysis, and well written for a forum post.

if you could find another similar xB and run the comparisons again, that would make for a VERY interesting read.

thanks for the info man.

 

No problem, i thought that it should be tested and put to rest sort of speak.. Especially since there are a ton of myths that surround the Silencer and exhausts.. Of course, this was a small scale test, but i thought it was interesting and fun reguardless of how small it was. The Xa owner is a co-worker so it was easily put together. If i could find a xb owner near here with a similar set up, i could do the test again. I have a feeling the results wouldn't change much, the problem with finding a near identical xb is the fact that it would boil down to driver with the controlled testing. But yeah.

 

Cool write upe, couple questions though.

Is this a full exhaust from the header (straight pipes)? Or exhaust with mid pipe..not just an axle back? After getting my (full) exhaust done with stock header, I noticed a big difference...that stock 1" mid pipe is restricting

 

Jic is an axle back, the piping is 2.25''. Although its just an axle back, i have yet to see another axle back respond as well to gains as Jic's does. I've been dyno'd as high as 96whp and as low as 93whp with my set up. Of course, more replaced piping the better.

I was going to use a test pipe and connect a muffler to it for a race set up, but it was way, way too loud. I did dyno once with that set up and obviously torque went down, but whp peaked 109whp @ 6,250rpm. I road around like that for a few days but couldn't stand how loud it was.

 

^ Rofl. Yea, a guy here in MN did that...sounded like a chainsaw on wheels. He rode on it for about a week, then put in a resonater and put the cat back in. Was funny though.

 

Yeah, sounds horrible but the power was nice. Ran out of rpms fast though once it revved closer to peak whp.

But yeah, the hks on the xa is also a axle back. We are pretty even with power i might have maybe 1-2whp more, but not enough to drastically alter any results. I also have weight reduction done to my box so the weight difference in reality is probably only 60-70lbs. Enough to make a slight difference, but again, shouldn't be enough to completely alter the testing and results. Finding another xb would probably make it more interesting for readers since it would be the same car, but who knows.

Lots of people viewing this thread, not enough comments. Let me know what you'd like to see tested and i'll do what i can do. Also, feel free to ask me any other questions.

 

i wanna b the other XB haha i but im not an auto......but yea for me i get more torqe with the silencer on for some reason prolly cuzz i have a universal muffler but sometimes i think i pull harder without it.......i dunno but my car just pulls diff from time to time not sure why but it just does......but yea great write up and experimenting