Today I’m very happy, as my exhaust issue is resolved.

NO DRONE WHATSOEVER.

I am very grateful to Jim at Tunehouse for his persistence with obtaining the correct exhaust from x-force…. Correct in the sense of being the same as what has been previously supplied to other customers, and capable of producing 400rwkw fairly easily.

As previously noted in this thread I was unhappy with drone produced by the exhaust, as supplied by x-force and fitted in Melbourne. This drone was very noticeable at 1800 to 2300 revs. When the exhaust was fitted in Melbourne Simon told me the mufflers were much smaller than what had previously been delivered.

Last week a new batch of x-force exhausts arrived in the country, and mid and rear section fitted today.

Visually, it was immediately obvious how much larger the new x-force mufflers were when compared to the old x-force..

The previous version of x-force mufflers was far too narrow, and overall too small in volume.

Here’s the relative dimensions:

Mid section muffler:

Height

New 155mm Old 130mm

Length

New 345mm Old 345mm : same

Width.

New 300mm Old 200mm……..major difference

Rear section muffler:

Height

New 160mm Old 150mm

Length

New 400mm Old 400mm : same

Width.

New 300mm Old 220mm……..major difference

So, the new mid section has a volume 80% larger than the previous x-force.

The new rear section has a volume 50% larger than the previous x-force.

The internal volume of these mufflers is very close to the standard factory exhaust (I’d say around 10-15% less due to them not being as long), and I’d say that the exhaust noise is very close to stock, marginally louder.

The x-force tips are not fitted, as I’m going to fit a stock exhaust tip, so the unsuspecting will think it’s a stock car!

Previous small x-force mufflers.

Tony at Tunehouse fitting at exhaust.

Note how much larger the new x-force rear muffler is.

Note how much larger the new x-force centre muffler is.

Again my thanks to Jim and Tony at Tunehouse for sorting this out.

As a customer it’s good to know that the alliance between Nizpro, Tunehouse and Xtreme (WA) can be put to good use, and the shared information is benefiting many forum members.

Next Jim will re-tune for a more aggressive tune, and more power, as the old 360rwkw seem very tame (although that’s what I asked for in my first tune).

Finally, if you are buying an x-force best to make sure you know what you are getting.

Brian

Looking nice Brian.

I was talking to Jeff yesterday and he says they have a custom built 4" exhaust that picks up over 30rwkw on APS's 3.5" system, with no other changes. 4" sounds huge and RDP say they only use them on cars making 600kW+.

And by the way my exhaust is street legal    

Hey BCL do the tips on the new xforce system line up better than the first one?

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My new x-force system is quieter than the APS, so there is no problem with the db limit. I've had enough of loud exhaust systems.

It may be too quiet for a lot of people!

Yes. Tips line up good.... but as I said I'm going to see if I can fit the stock exhaust tip.

Brian

Yes. Tips line up good.... but as I said I'm going to see if I can fit the stock exhaust tip.

Brian

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I'm interested to see how you go with that. I'm interested in doing the same thing.

I was talking to Jeff yesterday and he says they have a custom built 4" exhaust that picks up over 30rwkw on APS's 3.5" system, with no other changes. 4" sounds huge and RDP say they only use them on cars making 600kW+.

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I'd expect that most of that would be from the dump pipe, not because of the difference between 3.5" & 4" (33% larger flow area).

Can't comment on the cat, but I believe Jeff has sourced a very good cat.

It is not always a case of the bigger the pipe the better when it comes to exhaust. My understanding is that as power goes up the size of the front section of the exhaust and muffler back-pressure becomes more of an issue (plus cat of course), rather than focusing solely on pipe diameter. Also, as gas cools downstream you don't need as big a pipe diameter; more important to keep up the gas flow. For 600kw definitely wouldn't go smaller than 4".

When my blue car was in Melbourne the 4" exhaust was retained, but the mufflers had too much back-pressure, and custom mufflers were made. Even now, if I wanted to maximise power, the mufflers would be dropped on my blue car.

Brian

Couple of things I disagree about BCL,firstly the less restriction in back pressure on turbo charged the better,example quickest XR6T ran a 9.9 with NO exhaust

Secondly No good in using your 4" system that Tuffy's fitted as that is nothing like our custom exhaust, your system was fitted with untested and inadequate and wrong size mufflers where used thus the reason why you had to change mufflers and punch the cat

The system we have developed is a provern performance Exhaust and has outperformed both APS and X-Force systems

CV PERFORMANCE

Couple of things I disagree about BCL,firstly the less restriction in back pressure on turbo charged the better,example quickest XR6T ran a 9.9 with NO exhaust

Secondly No good in using your 4" system that Tuffy's fitted as that is nothing like our custom exhaust, your system was fitted with untested and inadequate and wrong size  mufflers where used thus the reason why you had to change mufflers and punch the cat

The system we have developed is a provern performance Exhaust and has outperformed both APS and X-Force systems

CV PERFORMANCE

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You didn't read my post too well.

I said that "if I wanted to maximise power, the mufflers would be dropped on my blue car." .... so you agree with me.

As for the Tuffy mufflers, they were not adequate when power was increased over 500rwkw, so again you agree with me. The cat was an older style from 3 years ago (was not punched) .... cats have come a long way since then.

The only thing left of that 4" system from 3 years ago is the 4" centre pipe and section over the diff into the dual 3". A larger dump pipe was fabricated off the larger turbo, and changes for the external wastegate, so the front section change was mandatory. Currently I'm not convinced that I should retain 2 mufflers at the rear, but there may be more testing on that in the future.

When you refer to x-force systems, given the number of combinations available (possibly as many as 10), you could be more specific. Can you publish the dyno overlay to support this?

Brian

Not a problem Brian I just dont want our 4" Custom exhaust associated with what was done by Tuffys

CON

Not a problem Brian I just dont want our 4" Custom exhaust associated with what was done by Tuffys

CON

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No worries; we've all (with exception of 1 person on this forum) moved a long way forward in the last 3 years.

I'm sure you guys have come up with something very good.

Brian