To downpipe or not to down pipe, URGENT :)

[TheVazha]

Hello gents,

There is a very nice young man that has offered me a set of DP's for the truck. My set up is such that I bought the truck for my newborn. I am working on an exhaust but I figure the exhaust is in the rear of the car and most of the "loud" happens at the tail pipe. I can live with that.

The down pipe is in the front of the car. Not that it's any louder there but certainly more is going on as the gasses are flowing unfiltered escaping the motor.

My question is, shoudl I do the DP's? Is do all the pros outweigh the cons? My choice would be DP's with stock mufflers or stock DP's with a Meisterschaft muffler system...

[mitch808]

Do it, if its a good deal do it and dont look back

[mhkm]

You bought the car for your NEWBORN??
And now you want to mod it with downpipes??

Unless you are training him to be the next Michael Schumacher, I do not recommend this mod...

However, if you are looking for more power easily and a great sound, like mitch said, go for it. DPs and stock exhaust is the best setup IMHO.

[protecon]

Catless DP don't add any more power.

[Cattivo]

I was in a similar situation having a 1 yr old daughter and wasn't sure if I should go catless...the gaseous odor will be noticeable only if you have your windows open at a stop sign or red light...keep your windows closed while the kids in the truck and you'll be fine...do it dp's with straight pipes!

[jrmccain]

Originally Posted by protecon

Catless DP don't add any more power.

I'm not certain that this is true since I didn't put my truck on a dyno before and after installation but I can say that the throttle response was vastly improved allowing me to experience the benefit of turbo boost quicker than before. So in that sense you can actually feel more immediate power output and throttle response. For me it was worth it and I'd do it again.

[mitch808]

Originally Posted by protecon

Catless DP don't add any more power.

Any turbocharged car, where you can remove exhaust restrictions, will unleash power when properly tuned for. Where do you get this statement or gross generalization?

An ideal exhaust would basically be the end of a Tuba, flanging off the Turbo exhaust. Not practical at all, but that would be ideal.

[TheVazha]

Thanks guys fro the discussion. It looks like I will be doing DP's as soon as I get my hands on a set.

Anyone have some laying around?

[protecon]

Show me before and after Dyno graphs showing at-the-hubs increase in power.

The only restriction catted downpipes (turbo-back dump pipes) cause is potential bottleneck for heat - this is the main driver for decat for the S63/N63 motors. BMW went to great lengths with the factory cats to ensure maximum airflow whilst maintaining compliance to emissions control.

I would not call this a performance mod, purely for the gains (if any) achieved vs cost.
Upgrading your fuel system, either through meth injection or installing larger injectors and tuning for E85, will net much better results for the money.

[TheVazha]

Pro, you're not the only person who's told me so. I just got off the phone with a tuner who shall remain nameless who admits cost vs. benefit makes this mod a non starter for a DD. Now, if you're trying to brake records you cannot do it without this mod.

If I can get a used set I'd do it just for the claim in my sig.

[JeST]

Catless or highflow cat downpipes + a tune does increase power.

[protecon]

A tune (whether modifying fuel/ignition maps/transmission/boost) will potentially increase power/torque at specific rev ranges - factory tunes are naturally designed for a "balanced" diet of performance vs economy.

You may have different tunes for cat/decat to delete CEL, but I wouldn't think these were based on calculated additional airflow (read performance) through your turbos due to decat.

There's lots of good discussions regarding performance mods on other forums.

[TheVazha]

Will these fit my car?

http://www.ebay.com/itm/Becker-Perfo...9bd3#vi-ilComp

[protecon]

No.

http://www.xbimmers.com/forums/showthread.php?t=1145909

Apparently they're too short for the S63 (despite being advertised to suit).

[Toneaero]

Originally Posted by TheVazha

Will these fit my car?

http://www.ebay.com/itm/Becker-Perfo...9bd3#vi-ilComp

I don't believe so. Correct me if I'm wrong but the N63 and S63 is different enough that the tight tolerance required of these pipes are not transferable. I thought I read once that the turbos are different between N63 vs S63.

[TheVazha]

Interesting, thanks for the advice. Someone on the other thread made a good point, how come other down pipes are advertised to fit across both X5M and X6M platform but these wont fit?

I winder if they make X5M pipes. I'll shoot them an email and report back..

[Toneaero]

Originally Posted by TheVazha

Interesting, thanks for the advice. Someone on the other thread made a good point, how come other down pipes are advertised to fit across both X5M and X6M platform but these wont fit?

I winder if they make X5M pipes. I'll shoot them an email and report back..

Thats not the issue. X5M and X6M are both S63. Therefore, parts work between the two chassis. The issue is that some eBay vendors don't know the difference between one 4.4L v8 from another.

Here is a good read on the differences between S63 and N63 engines: [delete space in the URL] http://www.bimmer boost. com/content.php?1157-BMW-twin-turbo-V8-analysis-Power-potential-tuning-performance-and-architecture-of-the-N63-and-S63-motors

[Dchl21]

Originally Posted by TheVazha

Interesting, thanks for the advice. Someone on the other thread made a good point, how come other down pipes are advertised to fit across both X5M and X6M platform but these wont fit?

I winder if they make X5M pipes. I'll shoot them an email and report back..

it smells

[protecon]

Originally Posted by Toneaero

I don't believe so. Correct me if I'm wrong but the N63 and S63 is different enough that the tight tolerance required of these pipes are not transferable. I thought I read once that the turbos are different between N63 vs S63.

Probably the main reason is the different N63/S63 exhaust manifolds deviate the turbo turbine exit positions.

[Cattivo]

The best thing about going catless imo...I was averaging 10.3mpg with stock dp's...ever since I had catless dp's installed I'm now averaging 12.2mpg

[Creamo3]

Originally Posted by protecon

Show me before and after Dyno graphs showing at-the-hubs increase in power.

The only restriction catted downpipes (turbo-back dump pipes) cause is potential bottleneck for heat - this is the main driver for decat for the S63/N63 motors. BMW went to great lengths with the factory cats to ensure maximum airflow whilst maintaining compliance to emissions control.

I would not call this a performance mod, purely for the gains (if any) achieved vs cost.
Upgrading your fuel system, either through meth injection or installing larger injectors and tuning for E85, will net much better results for the money.

So you're saying that removing a restriction from the exhaust path on a turbo charged vehicle isn't considered a performance mod? That is simply incorrect, while the performance benefits may not be great compared to a stock catted setup, there are definitely gains to be had. The best exhaust for a turbocharged vehicle is no exhaust or an exhaust with minimal restrictions. Catless downpipes are good for 20-30 whp on this platform. I have actually dyno'd my vehicle and compared to trucks with just a tune.

To the OP's original question, if you can handle increased emissions smells and sound then go for it. The best money spent on these is on a tune, the downpipes help some but not as noticable.

[TheVazha]

Good discussion guys, some great points made, thanks.

So, if you had $$$ to spend on the truck, would you do Downpipes or a set of wheels or new tires or carbon pieces or ________?