Exhaust manifold

[Marleez]

My exhaust manifold has failed, has anyone swapped their manifold for headers? Was the sound improved? I'm thinking to do this.

[Linas.P]

I am pretty sure many have done that in US, so it is not impossible... although it may be costly and complicated. First thing to consider is space - Lexus went with the basic design manifold design is because there is basically no space on the sides of IS250/350. One thing for sure - you not getting them of the shelves (there used to be few companies making them for astronomical prices, but I doubt they still have stock for discontinued product) and whoever makes them will have to make very intricate design. So you talking custom and intricate job to get them equal length and fitting.

Now the second part - the sound will depend on the design, well designed and flowing headers will sound better on their own (not this), but you will be restricted on the first point.

The third thing and the reason why I said "on their own", is because you won't hear much from the headers if you keep the rest of the stock exhaust. So we talking here about full custom system if you really want to benefit from the sound of the headers... and besides cars in UK will never sound as good as ones in US, because US ones are usually straight through exhaust with maybe resonator. In UK you have to keep cat, can be replaced to singular high-flow cat, but you must have one and the cat kind of muffles the headers.

In short - it will be very expensive, the sound improvement will be minimal, power improvement will be minimal (it is possible you even lose some power) and everything well be rather complicated. Don't want to discourage you, but it is not as simple as it may sound.

 

[Marleez]

Manifold are very expensive here. That's why I wanted to get a stainless steel headers? Bit if it decreases performance. Then I guess I'll have to go for oem manifold