BMW x5 4.8is (e53)- X-pipe or Straight Pipe?? PLEASE HELP

[pnoyako85]

oh i see.....although now..i Need opinion..on changing Cats......what is the best out there?>>............i may need new cats..and looking around and there alot of them out there..i heard FD 200 Cell are good...but what is really good ?..

[TwinsPoppa]

Originally Posted by pnoyako85

oh i see.....although now..i Need opinion..on changing Cats......what is the best out there?>>............i may need new cats..and looking around and there alot of them out there..i heard FD 200 Cell are good...but what is really good ?..

Sorry, I have no clue. However, you can't go wrong with the stock ones.

We all know what can happen when you start modding. Sometimes its tricky trying to make new things work together with the existing - the fit, performance, looks, reliability, etc.

Especially if you're the first one doing something.

[Nick P]

Originally Posted by pnoyako85

oh i see.....although now..i Need opinion..on changing Cats......what is the best out there?>>............i may need new cats..and looking around and there alot of them out there..i heard FD 200 Cell are good...but what is really good ?..

The N62 has Euro 4 emission standards, so 200 cell aftermarket cat could be risky in terms of passing the emission inspection. Normally, the afermarket high-flow cats could be used on cars having Euro 3 emissions standard, but I've heard, there's no such a thing as emissions control in many US states.

Since my X5 is registred in Russia, I did remove the cats, but installed some simple devices, which supposed to homogenise the exhaust flow, so the back pressure was there and I also installed very simple devices insted of stock resonator. Afterwrds my engine was remapped and I haven't seen any significant gains even with very rare Hartge headers exept for a huge torque increase at low rpms, but I suppose, this torque increase has nothing to do with exhaust, but rather with software, which had very mild tune especially at low rpm to spare the weak gearbox.

First I got measured 323 bhp with approx. 100 hp driveline loss having Hartge headers, cat-dummies, and these so called "sporty" resonators (which are basically tubes with some mesh inside around).

On the dyno chart you can see the huge torque increase after tune (more than 100 nm (75 lb ft) on some rpms.

Now with manual gearbox I have even less driveline loses and so more whp and also about 50 kg (110 lbs) less weight.

Next year I'll put the 200 cell cats and will do another dyno session.

My message was just not to mess around with exhaust, because the stock one is properly designed and tested in interaction with controlling electronics.