XJR sounds like a Kombi??

[SPman]

I've just replaced the standard, rusty steel collector box on the XJR with a Stainless Motad 4 - 2 collector. Now, the old girl sounds like a feckin Kombi (or a WRX if you want to be pretentious)! The pommy guys reckon they do that, but, why would a collector change the sound of a straight four into a flat four sound alike?

[Barfridge]

From what I've been told the sound of a flat 4 is more from uneven length headers.

[Drasius]

Yeah, there's a big thing about certain model scoobies when the header lengths were different between different regions (UK & US IIRC) causing quite a few complaints.

[Thirsty]

Yep the 2003/4 - 2006 Liberty's 2.0 twin scroll turbo models had equal length headers, they sounded more like a civic than a scooby.
When they went to the 2.5litre motor in 06/07 they fitted them back with unequal length headers cos it was a big complaint

[FJ Steve]

I'll respond to this tonight with the FJR version.. should be the same reason

[FJ Steve]

The FJR OEM collector box allowed exhaust gases from the 4 Cylinders to be distributed evenly between the left and right cans. 4-1-2.With my Holeshot headers, they are a 2 piece unit. Cylinders 1 & 2 are 'routed through to the LHS, cylinders 3 & 4 together with the O2 sensor, to the right.What happens is that with the firing order of the cylinders, you get a separate 'pulse' of exhaust, alternating between each exhaust can. This is what produces the 'off-beat', boxer style pulse under low to medium revs. You say that the new headers have a collector box, but is it open inside, or is it a 2 into one pet side?

And FWIW, my aftermarket headers are equal length each side.

[SPman]

No, it replaced the collector box - cyls 1&2 to one side, 3&4 to the other with a balance pipe

MCB.jpg

[FJ Steve]

I'd say it's the design of the new headers. Can't see the balance pipe being all that effective (in lieu of the OEM collector).

Wanna compare "off beat" exhausts?