I had heard clips of this exhaust on the net and read a lot of exhaust threads that talked about this exhaust. I had formed a belief that this exhaust sounded terrible. Since, I am doing some work on a Z and guess which exhaust was on the car; the injen (with kinetix resonated test pipes). The exhaust sounds fine at idle, good actually, but step on the gas and it is quite possible the worst sounding exhaust I have had (or will have) the displeasure of hearing on a Z.

Too add insult to injury, the piping is VERY small. I thought I was told, it was 2.25" duals. NO FREAKEN WAY. I threw up my trusty tape measure to the piping and found it was a whopping 2" OD! I'll grab a pic and post it up here for you doubters.

I know sound is subjective, so just take into account this is my opinion on the sound of the exhaust. The piping however is as objective as it could get.

 

Well, heres my opinion. I also have the injen exhaust, stock cats though.

I would agree that of most Z exhaust it def. has the least "exotic" sound. I wouldnt say it sounds horrible though.

My 2 cents: If I were to get an aftermarket exhaust again, it wouldnt be the injen. But I have it and like it.

 

Small pipe is only the half of it. Inside the back box there is a non removable silencer, like what other systems (and the earlier angle tip Injen) make removable at the tip. Here is a pic from the back



Here is a pic from the inlet side of the back box



Here is a little video I shot with a web cam attached to a piece of hose.
http://www.hypersprite.com/auto/vide...en_str_tip.wmv

I sold mine

Chris

 

pic I have of the piping

 

I love the exhaust because you can keep it as quiet as you want when shifting gears or your can make it mean as hell whenever you choose. When starting the car up and idling, it just rumbles and the sound is just beautiful. The only thing I can say is when crusing if your not around 3k and above the rumbling inside the cabin can get on your nerves a little bit. But in all to be totally satisify with this exhaust!

 

The silencer is fine. They should have put more resonators on the exhaust IMO. Are you complaing about it in terms of flow?

 

The resonators on this system are quite long, I think they do most of the silencing of the system. I really should have taken off the back boxes to see what it would have sounded like without them.

One of the things that gives this exhaust such an odd characteristic, it being loud until you get it over 3k, is that back box silencer. What I think is happening at low RPM is the gas slug is passing though it without it doing a whole lot, once you load the system, the larger volume of gas slows down at this restriction, forcing some of it to be diverted though the glass packing. This is not how this type of muffler is supposed to work. A glass pack, which this is, is supposed to absorb the sound, sort of like carpets hanging on walls deaden the sound in a room, the design was never intended to have the gasses pushed into it. This certainly explains the glass packing that blew out of so many of them and it explains why when you take a back box off after 3k miles and flip it end to end you can hear and feel the packing slide and thump each time, because significant amount is either no longer in the box itself or has been compressed down to one end.

One thing that makes me wonder about the Injen is how the front resonators use the same size perf tube as the exhaust but the back boxes go much larger but then are restricted. If you look inside the resonators you will see that they are perfectly made glass pack resonators. No restriction and completely smooth perf tube.

Another thing that makes me wonder is what affect the flange resizing has on flow. Having it go from 2" to 2.25" Flange | Flange 2.25" to 2" at each joint is not really the accepted way to build joints. Normally, if your system needs slack so you can adjust it, your output flange would be the same size as the pipe eg. 2" and your next input flange would be 2.25" and then step down. This was there is never a chance of a flat flange edge impeding flow, no matter how much adjustment it takes and this system can take a lot to get both back tips sticking out the same amount and at the same place in the cutouts.

Really, the pipe size in general has me curious, we all know OEMs will use as small of pipe they can get away with that will meet their coast / performance goals. In this case, the stock Y pipe tubing before it's merge is larger than the Injen tubing, doesn't that seem odd. Maybe Injen makes to many Civic systems.

Chris

 

i heard the clips to me it looks like top sp and helix etc sound hella better. for ugly exhuast topspeed does sound the best , but i do like the true dual aspect of the borla hks, my choice is gonna be the aps exhuast true dual