4.8 GRX free flow exhaust

[Rickster]

Hi Guys,

Can anyone advise me on the merits of a free flow exhaust system and are there any issues around removing the catalytic converters?

Many thanks

[Hermi]

Hi Ricster
Except for the nice sound,the purpose of the FF is more newtons and hopefully better consumption.
No need for converter worries.My 4.8 had nothing like that,just 3 boxes of witch one was not FF.I changed that and got rid of the first one and w-a-l-a----great sound.
Give 5 Kw more on dyno,but cant give saving results yet.

Hope this help.

[Saltman]

Hi Hermi

Did you remove all 3 standard Patrol boxes and replace with 2 free flow boxes?
The front (first) one being smaller than standard big non ff box and then the last small box?
I just did mine through Pwerlow and the sound is GREAT! Not too intrusive but if I put foot, it lets me know!
Still on the 1st tank, so not quite sure about economy, but I suspect the 1st tank won't count .. sounds far too great to waste on economy!
It feels as if there are some more torques as Jeremy Clarkson puts it, put I need to confirm on dyno!

Ons moet bymekaar kom en bietjie vergelyk!

[Rickster]

Hi Hermi and Saltman,

Did you only do the silencer boxes and not the manifolds and pipe? What are your thoughts on a wildcat branch and stainless pipe?

Regards

[David]

Show us some pictures

[Hermi]

Hello saltman

I have done my system twice.
First one with Roddey.He only took the big middle box out and replaced that with a smaller FF box.Sound was OK but i am full of ch---.I then talked to Frans and Martin Slabbert(who bought my previous 4.5)and went to do it over again.The outo sound was not acceptable.Martin and Frans was working on Martins 2.2 Toyotas years ago and the following trick was sold to me.

What i have done :
Remove the small front box completely and run a 50 mm pipe to the smaller FF box that Roddey put in.From there i ran a ,i think 75 or76 to the last origenal box.So from the flange to the middle box is only 50 mm.
There is no hummm coming at low rpm--being an outo box.But broer from 3000 rpm !!!!!!!!

Greetings
Call me 0823346246

[Saltman]

Ricster

I left my manifold and downpipes as they were. There is nothing wrong with that 6 into 2 downpipe setup on the 4.8.
It also has the sensors in it which I did not want to disturb!

I replaced the manifolds and downpipes on my Range Rover V8 with Wildcat branches 10 years ago. Great power improvement, but it came at the cost of less low down torque and serious under bonnet temperatures that still plaques the carburettion setup to date!!! Be warned. Not nice in the hot summer sands of Atlantis or Kalahari. Great for cold weather environments though ... so it depends where you live and what you do with it ...

Hermi, I replaced mine from the flange after the downpipe goes into 2 and then into 1.
I replaced from the flange rearwards with 63mm st/st pipe.
Having removed one box completely, I made the first section of pipe longer before entering the big free flow box. The setup now had the required length for the torque I needed, so from there it goes into 2 free flow boxes, the first being big, but a lot smaller than Nissan original and the second one at the rear being close to same size or even a bit bigger than original rear, but remember it is now free flow.

I am very happy with the sound and my gut feel tells me my midrange torque from 2000 rpm upwards is improved - and this is where I need it when I tow.
From 3000 rpm upwards it is alive! It definitely hits the rev limiter quicker!!!

[Rickster]

Thanks Saltman!