Been working with Fabooka (John) and decatted the stock exhaust on a remapped ASZ.

 

The long and short of it is...

 

It spools ever so slightly quicker/earlier but has done virtually **** all to performance.

 

Oh well at least I've saved around 5KG's, it cost me £85 to have a pipe welded in minus £45 for the cat so £40.

 

The idle noise is a little louder but a little more 'tinny' but other than the above **** all :p :(  :'(

 

With everyone doing these current, deflaps, filter changes, PD160 fitments etc the proper to test is to do before and after logging keeping variables as consistent as possible - although not quite a 100% short of measuring pressure drop etc (for these other mods) its a good indicator using VCDS etc.

Did you not have it re-remapped to take advantage of the decat or were you expecting results from just cutting it out on current map.

Just thinking Stage I to II etc

Who did your current map, is it switchable on any parameter like Revo or Shark?

Edit: just seen you have a custom map, I would have though the best way to get advantage from decat would be to get it on the rollers again to have your map tweaked.

Interesting, would it have an effect that the car is already mapped for a car that isn't de-catted or did you re-write the map?

 

Mufflerectomied too?

There was no difference really in MAF readings thus no changes to be taken into account, if there was the map would be tweaked you see?

 

Did'nt seem to have a negative effect on the current map/turbo.

 

As far as a bottom dyno goes, it didnt really seem to effect the power either it may seem to rev easier but that could be a placebo and due to the colder intake temps we are getting since its colder now.

 

I actually believe a muffler modification/removal (i like to call it backbox since were are not americans :p)  will not have any real effect on power either, the example on the internet are on a PD150 there is nothing on a PD130.

 

From what i read a complete after-market exhaust system will not increase power etc unless at hybrid level power.

You will never see huge gains on a diesel with intake/exhaust modifications like you do on petrol engines. They don’t rely on back pressure the same for one. I’ve read somewhere that the standard exhaust system is good for 220bhp before it starts to restrict flow... which I think is well beyond the scope of the standard PD130 turbo anyway?

 

I’m not saying they won’t make a difference when combined with other modifications once you start thinking about going past stage 1 power, but on a lightly modified vRS on their own you will see little if any gains. Maybe a couple of bhp if you’re lucky and a slightly improved throttle response.

 

 

The only thing I found when I decatted mine was it massively over boosted! John sorted this out for me when he mapped it though might spool slightly quicker but could be the noise fooling you into thinking it's quicker

It might spool faster, but the only way you make more power on a diesel (or any mapped EMS petrol) is to increase fuelling.

Correct assuming theirs an increase in airflow to maintain AFR.