HM headers and Lukey exhaust?

[WytWun]

Is it just a function of the extra weight and drivetrain components as I thought?

Your AWD is giving your KH more than 150kg head start (~10% more kerb mass than the KH). Not only that, but it is driving a lot more energy sapping drivetrain (somewhere in the vicinity of 50-60% higher losses than for an FWD auto based on dyno results I've looked at). The only things in the AWD's favour in this comparison are a 10% lower final drive ratio, slightly better cams (if the KH has #4s) and the most aggressive downshift points of any auto 3rd gen, but these advantages aren't anywhere near enough to balance the equation.

If you haven't already got the straight through muffler as others have suggested, it is by far the most bang for buck performance mod you will make. The AWDs do respond well to the HM headers due to the cost cutting design of the stock "collector" that joins the piping from each bank, but the reality is that the headers will cost at least twice as much as the muffler and deliver at best half the performance gain.

Unfortunately, as I've noted elsewhere, I believe that the AWD WOT upshifts are a bit too high (at about 5800rpm) for the stock engine/exhaust power/torque curves. I've not driven an FWD to know when the WOT upshifts happen in such cars but from the shift maps I would expect somewhere about 5400-5500rpm, which is closer to where I think the stock AWD upshifts should be.

[KWAWD]

Your AWD is giving your KH more than 150kg head start (~10% more kerb mass than the KH). Not only that, but it is driving a lot more energy sapping drivetrain (somewhere in the vicinity of 50-60% higher losses than for an FWD auto based on dyno results I've looked at).

As usual, WytWun, you're providing great info, thank you!

But I'm surprised now about the straight through muffler recommendation; so you're advocating that as being a much more significant mod over the headers with twice the performance gain?

Mal said earlier:

Changing your rear muffler from the stock twin outlet to a free flowing one will help BUT it will change how the car sounds. If you dont mind a little more noise and perhaps a little (only a little) drone then is fine.

I hate N&V. But I'm willing to try it if there's a noticeable improvement.
From what I understand, swapping the headers for the HM's will reduce some of the drone, so maybe I need to do both. I might just start with the muffler, sounds easier and cheaper?
Can anyone recommend any particular muffler? (I guess the OEM VRX are not available?)

[WytWun]

But I'm surprised now about the straight through muffler recommendation; so you're advocating that as being a much more significant mod over the headers with twice the performance gain?

Apart from the T join (instead of a proper Y join) between the banks in the AWD the exhaust system in the later 3rd gens was quite reasonable for a locally made family car, with the only difference between the "sports" badged (VRX, GTVi etc) cars and the others being the use of the straight through muffler (pretty much a Lukey LR-2779). Mitsubishi's published figures indicate the muffler would be worth 8kW (peak).

The info I have suggests that the HMs could be expected to show a gain of no more than about 4kW (peak - a little bit more than that is gained lower in the rev range).

[macropod]

The info I have suggests that the HMs could be expected to show a gain of no more than about 4kW (peak - a little bit more than that is gained lower in the rev range).

For some dyno charts, see: https://www.aussiemagna.com/forums/sh...=1#post1596077. On my TW VR-X AWD, the HM headers netted 9.6% more peak torque (20Nm) and 7.0% more peak power (7.4Kw) than stock. With HM headers, the output is more than the stock peak output all the way from 4400rmp to 5700rpm. At 5000rpm and lower, the HM headers consistently produce 8-10% more torque than stock.