Which one give more WHP Catback or DP's?

135-CS · 05-09-2008, 06:55 PM

As Adam from Riss Racing says we can expect a gain of 27whp/49wtq on his catless downpipes.

What gain we can expect from a Cat-Back???

Its worth it pay $1.5k when maybe you can expect good sound and more HP with catless DP's and stock Catback?

What you peoples think???

TunedM2C · 05-09-2008, 09:53 PM

I know I picked up some good hp with my catback (at least that's what the butt dyno says) but I'm thinking you might pick up more with the dp. I'm considering getting the catted RR dp to go along with my catback (second cat delete) setup.

Red135 · 05-09-2008, 09:55 PM

I am fairly positive that there is more hp to be picked up with the dp's. (Not to be read that there is no improvement from a cat-back.)

RobLS · 05-09-2008, 09:56 PM

I'm planning on maybe getting dp's in the future, not so sure about the cb

135-CS · 05-09-2008, 09:59 PM

I think that a good combination would be RR catdeleted dp,s with BMW performance exhaust (just the axle back).

Maybe a aftermarket catback with catdeleted dp,s would be too loud. Could someone confirm this???

Red135 · 05-09-2008, 10:14 PM

It is relative, for some it would be too loud (for me). For others, it wouldn't.

professor · 05-09-2008, 10:18 PM

this is a good topic. what i'd be curious to learn more about are the differences between a catted-dp setup with a stock exhaust versus and catback exhaust upgrade with stock DPs.

while i would favor a setup with RR catted DPs and a catback exhaust upgrade i think it may be an overkill.

i'd rather change one variable at a time and see what i get rather than changing too many! one thing does make sense to me though - a catback exhaust upgrade has more potential to save weight as well!

Shabadoo · 05-09-2008, 10:18 PM

It all really depends on the engine control software. Traditionally removing or swapping in better flowing cats (along with a cat-back exhaust) will net more substantially more gains on a turbocharged motor than a cat-back alone.

If it's a "torque-request" engine then you will see initial gains, but the system will dial these back eventually. Software tuned for a freer flowing exhaust would give you better gains in that case.

I don't know the control system on the 135, so I guess I'm not much help.

aus · 05-09-2008, 11:53 PM

BMW exhaust are very good. You'd have to make some big power for the cat-back exhaust to make a difference. DP are definitely going to make more power, with or without a tune/piggyback.

Neo187H · 05-10-2008, 02:04 AM

Downpipes are the single largest exhaust modification you can make to improve turbo charged power. They are the first and largest source of back pressure in the exhaust system with the cats right there so that slows the exhaust gases down and thereby slow the turbo down. Free-er flowing gases mean they go through the turbo faster, spooling it faster and letting it run more effiecent.

135-CS · 05-10-2008, 11:47 AM

The people of CP-E are expecting a gain of 10whp defenitly the dp.s should be one of the best mod since they imorive whp and sound!!!

Some one has a video on a 135i with RR catless dp,s and stock exhaust?

05-09-2008, 06:55 PM	#1
135-CS Second Lieutenant 16 Rep 282 Posts Drives: EVO8,EVO9,E90,E82 Join Date: Mar 2008 Location: PR iTrader: (1)	Which one give more WHP Catback or DP's? As Adam from Riss Racing says we can expect a gain of 27whp/49wtq on his catless downpipes. What gain we can expect from a Cat-Back??? Its worth it pay $1.5k when maybe you can expect good sound and more HP with catless DP's and stock Catback? What you peoples think???
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05-09-2008, 09:53 PM	#2
TunedM2C Brigadier General 829 Rep 4,190 Posts Drives: 2016 LBB M2 Join Date: Jan 2008 Location: Earth iTrader: (2)	I know I picked up some good hp with my catback (at least that's what the butt dyno says) but I'm thinking you might pick up more with the dp. I'm considering getting the catted RR dp to go along with my catback (second cat delete) setup.
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05-09-2008, 09:55 PM	#3
Red135 La Flama Blanca 27 Rep 1,545 Posts Drives: 1-series Join Date: Mar 2008 Location: Abq, NM iTrader: (1)	I am fairly positive that there is more hp to be picked up with the dp's. (Not to be read that there is no improvement from a cat-back.) __________________ AMS, Berk Technology, aFe, ER
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05-09-2008, 09:56 PM	#4
RobLS Major 29 Rep 1,193 Posts Drives: M3 Coupe Join Date: Aug 2007 Location: Near Perpetual Rain iTrader: (0)	I'm planning on maybe getting dp's in the future, not so sure about the cb
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05-09-2008, 09:59 PM	#5
135-CS Second Lieutenant 16 Rep 282 Posts Drives: EVO8,EVO9,E90,E82 Join Date: Mar 2008 Location: PR iTrader: (1)	I think that a good combination would be RR catdeleted dp,s with BMW performance exhaust (just the axle back). Maybe a aftermarket catback with catdeleted dp,s would be too loud. Could someone confirm this???
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05-09-2008, 10:14 PM	#6
Red135 La Flama Blanca 27 Rep 1,545 Posts Drives: 1-series Join Date: Mar 2008 Location: Abq, NM iTrader: (1)	It is relative, for some it would be too loud (for me). For others, it wouldn't. __________________ AMS, Berk Technology, aFe, ER
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05-09-2008, 10:18 PM	#7
professor Major 46 Rep 1,473 Posts Drives: Z4 M40i Join Date: Mar 2008 iTrader: (0)	this is a good topic. what i'd be curious to learn more about are the differences between a catted-dp setup with a stock exhaust versus and catback exhaust upgrade with stock DPs. while i would favor a setup with RR catted DPs and a catback exhaust upgrade i think it may be an overkill. i'd rather change one variable at a time and see what i get rather than changing too many! one thing does make sense to me though - a catback exhaust upgrade has more potential to save weight as well!
	Appreciate 0 Quote

05-09-2008, 10:18 PM	#8
Shabadoo Enlisted Member 3 Rep 36 Posts Drives: Join Date: Apr 2008 iTrader: (0)	It all really depends on the engine control software. Traditionally removing or swapping in better flowing cats (along with a cat-back exhaust) will net more substantially more gains on a turbocharged motor than a cat-back alone. If it's a "torque-request" engine then you will see initial gains, but the system will dial these back eventually. Software tuned for a freer flowing exhaust would give you better gains in that case. I don't know the control system on the 135, so I guess I'm not much help.
	Appreciate 0 Quote

05-09-2008, 11:53 PM	#9
aus Major General 892 Rep 9,032 Posts Drives: Odysse Join Date: Jul 2005 Location: Seal Beach, CA iTrader: (10)	BMW exhaust are very good. You'd have to make some big power for the cat-back exhaust to make a difference. DP are definitely going to make more power, with or without a tune/piggyback.
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05-10-2008, 02:04 AM	#10
Neo187H Private 3 Rep 72 Posts Drives: Join Date: Apr 2008 iTrader: (0)	Downpipes are the single largest exhaust modification you can make to improve turbo charged power. They are the first and largest source of back pressure in the exhaust system with the cats right there so that slows the exhaust gases down and thereby slow the turbo down. Free-er flowing gases mean they go through the turbo faster, spooling it faster and letting it run more effiecent.
	Appreciate 0 Quote

05-10-2008, 11:47 AM	#11
135-CS Second Lieutenant 16 Rep 282 Posts Drives: EVO8,EVO9,E90,E82 Join Date: Mar 2008 Location: PR iTrader: (1)	The people of CP-E are expecting a gain of 10whp defenitly the dp.s should be one of the best mod since they imorive whp and sound!!! Some one has a video on a 135i with RR catless dp,s and stock exhaust?
	Appreciate 0 Quote