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The Nav is now De-Catted

21K views 89 replies 26 participants last post by  lookskyward1 
#1 ·
Decatted the Nav over the easter hols.
First impressions -WOW. deffo release a few extra ponies, Pulls hard through out the rev range
Smoke levels seem less :shock:
More diesel smell aparrant on tick over, but this my be due to the nav being indoors at the time.
Will give it a good run tomorrow and see if there is any differances in MPG etc......

Cat off the Nav and on the bench, in the process of seperating it to get inside it.



The ceramic cat internals



The internals removed, cat put back together and refitted to the nav



Took just over 2 hours to do, and didnt snap one bolt :thumbleft: :lol: and didnt cost me a penny! :D
 
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#6 ·
I was planning to do this over easter too but ran out of time (possibly due to moping around most of sunday with a corking hangover :roll: ).........

job for this weekend methinks.....

keep us updated of your observations.... :thumbleft:
 
#8 ·
Done-it-all said:
Has the sound changed any ? Has it is still on a standard exhaust.
Sounds exaclty the same matey and im still using the standard exhaust

WindowsWorld said:
Hey Andy.

Do you think this will improve MPG slightly ?

Leon
CAnt really comment at the mo as ive been T**Ting it around since i done it :lol: but im going for a good run tomorrow.

kallie said:
Excellent :thumbleft: how's the knuckles :?: :lol:
well they are bloody and battered :lol: all in the aid of power thou :thumbright:
 
#10 ·
sean84 said:
well andy, just curious but you make it sound like you removed the baffles and sh*te in a way that you can replace them, or are they fooked??? just curious as i usually had to use a hammer.
I was really carefull, using a long feeler blade round the edges and a screwdriver and it just popped out. :D

This isnt mine, i forgot to take a pic of the internals, its taken from another member who did the same. but it can be done with care.

 
#12 ·
THe Cat and turbo exhaust can be use again ? ?...without cat should thicker smoke compare with cat rite ?
 
#13 ·
jackhon said:
THe Cat and turbo exhaust can be use again ? ?...without cat should thicker smoke compare with cat rite ?

Smoke is actually less belive it or not :D

Also i can now see why the euro 4s have less power and higer fuel consuption comapired to a euro 3.

Warpas euro 3 cat is half the size of my euro 4. my cat had 2 "baffles" inside it also as opposed to prob only one in warpas

reset the fuel computer and sat on the motorway for 20 miles at 70 mph and for the first time ever my Display showed over 30 mpg, it hit 32.4mpg!
Standard form my truck would do approx 26 mpg @ 70mph
Remapped it did approx 29 max @ 70mph
Decatted with remap it did 32.4mpg @ 70mph

With just the remap and the way i drive i was averaging approx 26.2 mpg so not bad considering my lead foot, but with the decat its now showing 27.8 mpg.
 
#15 ·
tuju77 said:
ok which one better, a 3" exhaust or a decat
3" exhaust will be wasted if not decatted anyway, plus a lot say that unless you have a lot of other engine mods 2.5" is the right size for what we have. Mine just passed the MOT with no cat so emissions are ok.

I dont notice anymore mpg decatted but mine was good on euro 3 anyway, the cats look identical apart from size, the baffles in mine are the same but a 3rd of the distance between them.
 
#19 ·
sean84 said:
cheers andy, so is it worth doing to a euro3??? i suppose why not when its free, but will there be a noticable difference???

Mine is euro 3, did i notice a difference...very hard to say really, maybe at high revs but i need a rolling road done on it again. Having no decat but a new exhuast DID make a difference, but again i like to back things up with a rolling road.

I went from a remap 191 BHP to 200 BHP with exuast, just need to get a new rolling road done for the decat, will be done by the end of the month. I need to get two done as i have a RR down the raod from me, but up untill now all are from the same road to keep things constant :thumbright:

Will get another RR done if you manage to come up with the goods :thumbright:
 
#20 ·
Even my mate that runs a custom exhaust place said that 2.5 inch exhaust system would be the max he would do running the standard turbo etc....

as for performace, yes i have noticed a difference, there are no flat spots, turbo comes alive quicker and get a right kick in the back when taking off, but notice it more higher up the rev range as the revs pull round alot quicker.

As for doing the job, i was lucky to have a 4 post ramp to use.

You need to remove the 10mm bolts that hold the heat sheald in place around the top of the turbo, you can get your hand it to feel around to see where all the bolts are, when removed move the top sheald to the side and the back sheald to the bulk head.

you will now see the 3 17mm bolts that hold the cat to the turbo, removed these.

now from under the car, removed the 3 14mm bolts joining the cat to the exhaust.

Now looking up from under the car, the cat is held in place to 2 brackets with 14 mm bolts. one at the front of the cat and one at the side just above the prop. remove these.

There is one 10 mm bolt now to be removed and can be seen from the inside the passangerside wheel arch if you pull the inner plastic arch back a bit, remove this.

The cat should now be ready to remove. once removed you will see the 5 14mm bolts that need to be removed to seperate the cat.
you will see the internals that need to be removed. either take a drill to it and drill it all out or use a long feeler blade and screwdrive to pop it out.

Put back together and refit.

took me just over 2 hours put i was luckly enough not to have any seized or snapped bolts.....
 
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#22 ·
Warpa said:
tuju77 said:
ok which one better, a 3" exhaust or a decat
3" exhaust will be wasted if not decatted anyway, plus a lot say that unless you have a lot of other engine mods 2.5" is the right size for what we have. Mine just passed the MOT with no cat so emissions are ok.

I dont notice anymore mpg decatted but mine was good on euro 3 anyway, the cats look identical apart from size, the baffles in mine are the same but a 3rd of the distance between them.
Mine is already 3" no cat but considering putting back the 2.5" decat since with 3" it seems that the torque move up a bit, abit sluggish low end since my ecu has been tampered by stupid dealer
 
#23 ·
Right decat done :shock:

Initial observations..........

On road test it seemed a bit more responsive, scorpion exhaust had slightly more of a rasp, but.............................. lots of smoke!! :(

Will do an ECU reset now and see how it goes.

Also when I got back from an enthusiastic road test it seemed very hot, lots of ticking and some smoke!!!! :shock: (am hoping that was just the wd40 burning off).

My cat would not come out undamaged :( both the copper rings fell off and I had to hammer it out with a block of wood. Its still in one piece but has some dents in it now.......... so am praying all is ok

PS. the back bolt where the pipe bolts on to the turbo is an absolute bugger to get to.....................
 
#24 ·
paul_w_100 said:
Right decat done :shock:

Initial observations..........

On road test it seemed a bit more responsive, scorpion exhaust had slightly more of a rasp, but.............................. lots of smoke!! :(

Will do an ECU reset now and see how it goes.

Also when I got back from an enthusiastic road test it seemed very hot, lots of ticking and some smoke!!!! :shock: (am hoping that was just the wd40 burning off).

My cat would not come out undamaged :( both the copper rings fell off and I had to hammer it out with a block of wood. Its still in one piece but has some dents in it now.......... so am praying all is ok

PS. the back bolt where the pipe bolts on to the turbo is an absolute bugger to get to.....................
Hi Matey. the smoke will be the WD40 burning off mine did the same :lol: but as for lots of smoke out the exhaust, i deffo dont have that problem...i have less if anything! :shock:

The first time i drove it it blasted a lot of smoke but it soon settled after a blast down the motorway and a ECU reset.

Are you running a DTE or anything???
 
#25 ·
ok, it seems better than my 3" but now everytime I give the pedal a kick in any RPM, I can hear a whistling sound just for a brief moment, sound like the turbo, it wasn't there before, anybody experience this
 
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