Ok guys. I'll start by quickly introducing myself. I've recently purchased an XR6T auto. Mods so far are Capa Edit 8psi Map and K&N filter. My previous car was a 200sx S15, so as you could imagine I am extremely happy with the torque and power delivery of the 4L DOHC donk.

Anyway... back to the problem at hand. I decided to book the car in at my local exhaust shop to remove the centre muffler. I wasn't in the best frame of mind at the time and must have said something about the rear muffler, however meaning the centre muffler. So I get the car back and he has removed the very rear muffler and replaced it with 2 x 2 1/4 pipes with the old tip welded on.

I thought I would try it out and see what it was like. How dissapointed I was, immediately I noticed a drop in mid-range power. Top end did improve however. It was quite amazing how much affect this has placed on the performance of the car. It's like there is major turbo lag all the way to 3,500rpm.

So I rang the exhaust shop and explained my / there mistake and he was very good about it, told me to bring it in the early the next morning. So today I have dropped it off and he is going to remove the centre muffler and replace with 2 x 2 1/4" bends with resonators. He mentioned that he will keep the other mod in place so that leaves only 2 resonators in the entire system. Obviously this is going to be a bit loud.

The question I am asking is, has anyone else performed a similiar mod and are happy with the performance and sound? I can see myself taking it back and getting another muffler or resonator put on the rear to quieten it.

It's amazing how something so simple has turned to sh!t. I suppose it's my own stupid mistake. I feel like throwing the entire cat back to the sh!t heap and purchasing a pre-fabricated system.

Any feed back relating the sound and performance affects would be appreciated.

Thanks.

RJS has done this, was very happy with the sound. It sounded brilliant.

He did notice a massive reduction in power, and that was proven at a dyno day. Lost about 20rwkw from removing rear muffler.

Could anyone explain why removing a restriction like a muffler decreases performance on a turbo car like the XR6? I have always been under the impression that turbo cars benefit from less restriction in the exhaust? This being my 3rd turbo car, I'm not what you call a newbie.

Fair enough if I still had the factory mapped ECU, but with the edit I thought this wouldn't be the case....

Very confused.

Hey 2far, as a previous S15 heavily modded owner, mate do yourself one favour.

FORGET EVERYTHING you did to your S15 , it was a simple set up for BOV, more boost, exhausts, pods etc. These things are totally different and quite frustrating. The ECU is TOO inteligent and keeps f*cking up any of these sorts of "simple traditional tirbo mods".

Do heaps of reading on this forum and you will easily learn the right way to power up this car. :laughing:

So I better start looking for a second hand rear muffler then.... Geez this has been more trouble than its worth.

Can't understand that at all - unless there is some humungous difference between the exhaust systems on utes and sedans. When I removed the rear muffler of my son's ute it went no different than before - just sounded a helluva lot better. In otherwise standard form it did 14.3 at Townsville, which is a notably slow track, so it certainly wasn't down on power. Utes are 150kg heavier than sedans too.

PS Bumometers can be very deceiving. Maybe because you "feel" it goes better up top you just "feel" it is slower down low - it is all a comparative thing. Only a before and after dyno could really resolve this kind of issue. Most people's bums cannot feel the difference in a 10% power change.

I can definitely notice the power loss. Put it this way, I can't even here the turbo whistle at all, only when the vehicle is reving past 4,000rpm.

If I am coasting along at 60km-70km and I plant my foot, the car drops down a gear and goes like an Excel.... Where as before the thing would go like a cut snake and even loose traction.

........PS Bumometers can be very deceiving. Maybe because you "feel" it goes better up top you just "feel" it is slower down low - it is all a comparative thing. Only a before and after dyno could really resolve this kind of issue. Most people's bums cannot feel the difference in a 10% power change.

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Except of course for Cro's bum which is calibrated to +/- 3kW seasonally adjusted.... but only when going backwards...with his lights on. _

Can anyone recommend a place in QLD that sells aftermarket exhausts? Maybe something like the XFORCE? I'll cut my losses and purchase a complete cat back system.

I can definitely notice the power loss.  Put it this way, I can't even here the turbo whistle at all, only when the vehicle is reving past 4,000rpm.

If I am coasting along at 60km-70km and I plant my foot, the car drops down a gear and goes like an Excel....  Where as before the thing would go like a cut snake and even loose traction.

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I'm not convinced yet ... what is making your turbo whistle? Is it load on the turbo making it whistle do you reckon? You say it now only whistles above 4000rpm so did it whistle below 4000rpm previously?