[vasillalov]

So on Wednesday I had catless downpipes and catless exhaust installed on my otherwise stock N54.

It may be a bit too early to be 100% sure, but it seems to me that the car has lost a bit of its low-end torque. The engine does rev bit faster and feels more responsive, but somehow it feels that it lost a bit of its low-end oooomph.

Is it my mind playing tricks with me or indeed the increased exhaust flow reduced the low-end torque of the engine?

Any ideas?

[shifterboy45]

Originally Posted by vasillalov

So on Wednesday I had catless downpipes and catless exhaust installed on my otherwise stock N54.

It may be a bit too early to be 100% sure, but it seems to me that the car has lost a bit of its low-end torque. The engine does rev bit faster and feels more responsive, but somehow it feels that it lost a bit of its low-end oooomph.

Is it my mind playing tricks with me or indeed the increased exhaust flow reduced the low-end torque of the engine?

Any ideas?

why would you go catless??? what benefits were you looking for?
more power? was the car performing badly in its stock configuration? but then again, you may have answered your own question

[vasillalov]

No, car ran great before the install and runs great even with the catless system. I went full catless because I want more power. I have a list of mods coming in to supplement the exhaust system.

[bulldog_yyc]

you will need a tune to take full advantage of your exhaust setup

[vasillalov]

Originally Posted by turkish335

you will need a tune to take full advantage of your exhaust setup

That I am fully aware of! I am waiting on certain tuners to release their Stage 2 software. In the mean time, I am upgrading the hardware...

[mdash]

It is very common to see a loss in low end power when you install a "free flowing" exhaust system. Less backpressure in the exhaust is the reason. It will be much better once you get your tune as timing and boost levels will be adjusted and any loss you feel now will be null and void with the tune.

[RoundelM3]

Just curious...I heard from a shop that I used for years that removing the catalytic converters was a violation of the Federal emissions standards and could result in up to a $10K fine. Anyone have any other info on that? In some states' annual inspections, they check to see if they are there, others use a tailpipe "sniffer", etc., and in either case, the car won't pass. How are those who choose this path getting by the emissions laws in their states?

[RiXst3r]

Originally Posted by vasillalov

So on Wednesday I had catless downpipes and catless exhaust installed on my otherwise stock N54.

It may be a bit too early to be 100% sure, but it seems to me that the car has lost a bit of its low-end torque. The engine does rev bit faster and feels more responsive, but somehow it feels that it lost a bit of its low-end oooomph.

Is it my mind playing tricks with me or indeed the increased exhaust flow reduced the low-end torque of the engine?

Any ideas?

Indeed. I have seen this same thing, and with a boost gauge and OBD logger, you can really see what is happening. Throttle closure and boost target overshoot.

The stock boost control system has to adjust to the loss in backpressure. You are making it easier for your turbos to reach their boost targets., so at first you will see the car overshooting its boost target and then pulling boost way back and then it shoots up again... you also get more throttle closure. Some of this will adapt itself out, but you really won't see major performance benefits of catless without a tune.

-Rick

[marconi118]

reduced back pressure is always good for a turbo car even at low RPM

The turbo itself provides the needed back pressure to the engine.

So leave it free flowing !

[shifterboy45]

Originally Posted by RiXst3r

Indeed. I have seen this same thing, and with a boost gauge and OBD logger, you can really see what is happening. Throttle closure and boost target overshoot.

The stock boost control system has to adjust to the loss in backpressure. You are making it easier for your turbos to reach their boost targets., so at first you will see the car overshooting its boost target and then pulling boost way back and then it shoots up again... you also get more throttle closure. Some of this will adapt itself out, but you really won't see major performance benefits of catless without a tune.

-Rick

yeah, just what he said^

most cars that have really restricted exhaust systems will benefit from a better (freeflow) exhaust system. BMW tuned this overall exhaust pretty well for stock use.

now when you start using power adding mods, this change will be welcome.. and throttle response/torque delivery wont be inhibited by a sub par system.

but youll note that most tuners stage one tune is still good for use with the stock exhaust.

sounds like you going past that.. right ?

[vasillalov]

Originally Posted by shifterboy45

but youll note that most tuners stage one tune is still good for use with the stock exhaust.

sounds like you going past that.. right ?

Definitely! Other supporting mods include:

1. HPF Intercooler
2. GIAC Stage 2 or Stage 2+ when available
3. Forge DVs
4. Modded stock intake box
5. LSD Diff + better clutch once the stock one gets toasted

[OpenFlash]

Originally Posted by marconi118

reduced back pressure is always good for a turbo car even at low RPM

The turbo itself provides the needed back pressure to the engine.

So leave it free flowing !

+1

[Alexander]

Originally Posted by vasillalov

No, car ran great before the install and runs great even with the catless system. I went full catless because I want more power. I have a list of mods coming in to supplement the exhaust system.

Originally Posted by turkish335

you will need a tune to take full advantage of your exhaust setup

Originally Posted by vasillalov

That I am fully aware of! I am waiting on certain tuners to release their Stage 2 software. In the mean time, I am upgrading the hardware...

Originally Posted by roundel335

Just curious...I heard from a shop that I used for years that removing the catalytic converters was a violation of the Federal emissions standards and could result in up to a $10K fine. Anyone have any other info on that? In some states' annual inspections, they check to see if they are there, others use a tailpipe "sniffer", etc., and in either case, the car won't pass. How are those who choose this path getting by the emissions laws in their states?

Yes you will need a tune to utilize the change in air flow and back pressure.

I just got my emissions tested today. In NC they just check for codes.

It depends on your state, I'm sure in California they will ass rape you if you are caught.

[ar design]

You need a tune, without question.

[RoundelM3]

Originally Posted by Aonarch

Yes you will need a tune to utilize the change in air flow and back pressure.

I just got my emissions tested today. In NC they just check for codes.

It depends on your state, I'm sure in California they will ass rape you if you are caught.

Here in Texas they will (pardon the pun) cut your nuts off if you get caught without cats after your tailpipe sniff goes off the charts and they start checking for the obvious causes.

[Brey335i]

Originally Posted by roundel335

Here in Texas they will (pardon the pun) cut your nuts off if you get caught without cats after your tailpipe sniff goes off the charts and they start checking for the obvious causes.

Catback exhaust + change back to stock DP's for the State Inspection

[mhkm]

Loosing low-end torque ????
So on Wednesday I had catless downpipes and catless exhaust installed on my otherwise stock N54.

It may be a bit too early to be 100% sure, but it seems to me that the car has lost a bit of its low-end torque. The engine does rev bit faster and feels more responsive, but somehow it feels that it lost a bit of its low-end oooomph.

Is it my mind playing tricks with me or indeed the increased exhaust flow reduced the low-end torque of the engine?

Any ideas?

Can you be more specific? Did you have catless downpipes before, and now have gone catless, or were you stock before?? That is VERY unusual IMHO, to not see a substantial increase in power, even at low end, with installing downpipes, catless or catted.
The gain I saw was like night and day after installing catless downpipes!!

[vasillalov]

I went from stock to fully catless.