2.25" Or 2.5" For Centre Muffler Replacement

[Hazey]

I am considering doing the Centre Muffler removal mod. I have done lots and lots of researching and have come up with the following:

Replace the Centre muffler with 2 x 2.25" Hotdogs as this seems to have fixed those that experienced a bit of drone with having just replaced with pipes.

Why 2.25 and not 2.5, read further below.

Droning:

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I would like those that have done the above to post what size pipes they replaced with, be it 2.25 or 2.5 and if they experienced any droning what so ever. (Is is possible that the only ones that droned were 2.5" not the 2.25")

Power Increase:

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Some people said they noticed slight increase others alot more (some have dyno proven figures)

What about people that reported 10rwkw+ increase (e.g test from zoom magazine)

Could it be that those that went 2.5 only had a slight increase and those that went 2.25 ended up with 10+rwkw?

Read on..

A User on this forums 56Mainline found the following:

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"Replacement of the centre muffler with 2x 2.25"

* Power and torque are up right across the rev range.

* Peak power was up by 14rwkW at around 5000rpm, and torque at peak power was up by 55Nm.

* Mid range power was up by a maximum of 21rwkW (approx 2800 to 3500rpm).

*Bottom-end through to 3000rpm saw torque increase between 70 and 80Nm. And you notice it when you drive her!

* The greatest difference/improvement is in the lower to middle rev range.....where it is useable!"

Instead of using the 2x 2.25 he used single 3" and I quote "system did give improvements in both rwkW & torque right across the rev range, but at only around half (!!!) of the improvement achieved by the 2x2.25".

Thanks for reading, if commenting lets keep on topic.

Cheers

Aidan

[bugster70]

Just subscribing to this thread 'cos I'm also hoping to do exactly the same mod (eventually :( ) and am very interested to hear about others' experiences.

[BLK6T]

Same I want this also but want to do it right.....so I will wait to see what replys come, hopefully there will be someone in sydney with this done and I can possibly hear and see...

[fordboy1981]

I have 2.5" mentral bent with no hot dogs...it's a bit drony when it's cold, but once it's warm it sounds ace!

Dave.

[jordak]

I heard a number of forum members complaining about the straight through pipes causing droning regardless of whether 2.25" or 2.5" were used. As aresult I went straight for the twin hotdog version which consisted of twin 2.5" pipes leading to twin 2.5" mantra hotdogs then back to twin 2.5" pipes. Pipes were mandrel bent and joined to the existing system by flanges.

The result was a nice note that is not too loud however more throaty and deep. It sounds particularly nice on start up and well as providing a nice burble when backing off the accelerator.

Performance wise it did seem to provide a little more low to mid range grunt as well as a slightly improved trottle response. These improvements however in no way equated to the level of rwkw increases others have reported.

I would be cautious if you are expecting huge performance gains as I this did'nt occur in my case. The improvement in sound as well as the minimal performance gain was definately worth the $300 odd bucks it cost me.

A definate winner as far as mods go even if you are likely to replace the wjhole system further down the track when chasing big kw gains as you can simply unbolt it and on-sell

Hope this helps the decision process!

Steve

[ZAP]

I got 2 x 2.5" hotdogs to replace my center muffler.

I only did it because my center muffler was damaged by my driveway.

The sound is great, but I do not have any drone. I also did not notice any seat of the pants power improvement. It only cost me $200 for the work.

[bugster70]

Great answer, thanks Steve. Just got one question relating to your post - when you have the flanges put on the new part of the system ie. the hot dogs, do they bolt straight on to the existing system? I mean, does the stock system already have flanges there so the centre muffler can be easily replaced, or do you have to weld flanges onto the stock system too?

[jordak]

Great answer, thanks Steve.  Just got one question relating to your post - when you have the flanges put on the new part of the system ie. the hot dogs, do they bolt straight on to the existing system?  I mean, does the stock system already have flanges there so the centre muffler can be easily replaced, or do you have to weld flanges onto the stock system too? 

<{POST_SNAPBACK}>

The stock system already has flanges in place making it a simple changover if needed.

[xr6t ute]

2 1/2 with hot dogs, sounds better and no drone but didnt notice any power improvements

Shane

[Goobz]

I'm hoping to do the same thing, but with a cat replacement aswell. Maybe dump pipe. I'm tossing up whether to do this or go a full 3 1/2" system.

Chris