Free Flowing Exhausts for LandCruiser 100 Series Petrol (1FZ-FE)

Hi, I can't help you specifically with advice on the 1FZ-FE but I found a 2.5 inch free flow exhaust to be worthwhile on my RB30 Nissan Petrol Engine. The biggest improvement came between 3500-4500 revs (ie when overtaking in 4th gear). I can stay in 5th gear down to 60 km/h now on flat or downhill roads so the economy is available if you drive economically. Conversely the extra power available at higher revs will use more fuel. It all comes down to your driving style, but in summary you should definately get more economy and/or power.

I forgot to mention that I also have extractors fitted. The extractors came first which boosted power/economy and then the free flow system further boosted the power/economy.

I find that I can save up to a litre per 100kms with the extractors/free flow if I drive conservatively, although I do tend to use the extra power when needed which doesn't help the economy. My 2.5 inch system and extractors fitted was under the $1000 mark from memory.