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Discussion Starter · #1 ·
I just installed my Cobb AP with the stage 2 beta maps along with my non resonated y-pipe on my 2010 and the performance increase was substantial. The throttle response is quicker and the pull from midrange on up is great. My next step to to get a custom tune, but thought maybe I should consider downpipes and then get the custom tune.

How much more power will I gain with the downpipes? I assume it will not be as significant as changing out the y-pipe. I am guessing a tune and y-pipe gain about 70 whp. How much more will downpipes add on top of this?

Thanks
 

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Yes chaining to down-pipes with no catalytic's reduce spool up time by 200-400rpms, Also allow for leaner A/F mixtures and more exhaust flow. All of those things add power.

Typically that adds 20-30whp with tuning. Only problem is generally once you go past a mid pipe, you are pushing the MAF sensor reading and Injectors past 100%. To safely add the 20-30hp, I recommend upgrading the intakes to 3" and adding larger fuel injectors, both as a safety factor, along with your custom tune.
 

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Discussion Starter · #3 ·
Yes chaining to down-pipes with no catalytic's reduce spool up time by 200-400rpms, Also allow for leaner A/F mixtures and more exhaust flow. All of those things add power.

Typically that adds 20-30whp with tuning. Only problem is generally once you go past a mid pipe, you are pushing the MAF sensor reading and Injectors past 100%. To safely add the 20-30hp, I recommend upgrading the intakes to 3" and adding larger fuel injectors, both as a safety factor, along with your custom tune.
Sounds like the DP's quicken throttle response, which I like. Do you feel the gain throughout the power band or is more on the top end? I will also research intakes and injectors.

Thanks for the information.
 

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Yes chaining to down-pipes with no catalytic's reduce spool up time by 200-400rpms, Also allow for leaner A/F mixtures and more exhaust flow. All of those things add power.

Typically that adds 20-30whp with tuning. Only problem is generally once you go past a mid pipe, you are pushing the MAF sensor reading and Injectors past 100%. To safely add the 20-30hp, I recommend upgrading the intakes to 3" and adding larger fuel injectors, both as a safety factor, along with your custom tune.
I don't think you need to go to 3" intakes, which IMO are not a worth-while secondary upgrade on stock turbos (meaning that if you have 2.75" to stick with those but if you are stock and looking to add an intake, go 3"). The reality is that you will likely be tuned in SD which makes the MAF issue go away and the 3' intake will not create any incremental power over the 2.75".

To answer the OPs question, Bill is right on. IMO the quicker spool is the best part.
 

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Downpipes, injectors + tune here on a 2011, I destroy stock 2012s. & walk P600 tuned DBAs. No intakes.
Catless DPs...great sound imho but crazy carbon buildup on bumper=clean it after every drive.
 

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Downpipes are a VERY effective power adder. My entry level package to customers usually consists of downpipes, midpipe and a tune as they are the three most potent things you can do to a stock GT-R.

Eric
 

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25 more HP based on 2012 GTRs with everything else the same including tuner. Pros: better sound, quickier spool, more HP. Cons: on gas it smells and adds a bunch of carbon out the exhaust.
 

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I had catless downpipes with an HKS middie. The exhaust was very stinky, until I switched to a Cobb catted middie. Once warmed up a little the odor is virtually non existant. The sound levels are exactly the same, maybe even better with more burble.
 

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Downpipes are a VERY effective power adder. My entry level package to customers usually consists of downpipes, midpipe and a tune as they are the three most potent things you can do to a stock GT-R.

Eric
Hi Eric Hope all is good at AMS. Eric would the downpipes make more power & torque at this point of an upgrade program than adding say 3" intakes with injectors on a car making around 530 / 550 whp?......What I'm getting at here is which should be the priority upgrade. I am planning all these additions on my 2010 at some point I hasten to add.
 

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What does AMS believe is the "trade-off cost" in HP, between their Catted and non-catted downpipes?

Alexd
 

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I would love to have the extra power, but the smell and carbon build up are really holding me back. I like to drive the car with no issues, I don't want to compromise drivability for a few whp. The midpipe and AP give a good amount of power, and have less negatives than dp's.
 

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I had catless downpipes with an HKS middie. The exhaust was very stinky, until I switched to a Cobb catted middie. Once warmed up a little the odor is virtually non existant. The sound levels are exactly the same, maybe even better with more burble.
I have Titan catless DPs & the Cobb mid setup, like Goodwood. No smell or soot on rear fascia issues. Also, it's not too loud--very sharp @ WOT--I get compliments from people on the sound.

The DPs will add 25-30 as stated. I would say they are cost-effective & good bang for buck, IMO...
 

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That's a tough one but I would lean more towards doing the downpipes first and doing the injectors intake shortly after that. Reason being that you would really not take advantage of the injectors and intake with stock DP's

On a car like yours Alex it would very minor... maybe 5-7 Hp? we use some pretty nice cats so they don't hold back too much on stock turbos.... bigger turbo's are a different story.

Eric
i have AMS DP & love them, along with HKS Res MP.
Smell is not bad but I do notice it.

How much power is lost is Cobb Catted MP?

Thanks, A
 

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I would love to have the extra power, but the smell and carbon build up are really holding me back. I like to drive the car with no issues, I don't want to compromise drivability for a few whp. The midpipe and AP give a good amount of power, and have less negatives than dp's.
This is the same debate I've been having with myself for over a month now. Decided I'd start with a midpipe and tune (picking a midpipe that will work well with additional mods if I choose to go that route). Figure I'd do this for a bit. If I want more later, I may pick up the AMS downpipes when I add a catback exhaust, but I will have at least one set of cats somewhere. I don't think I personally could stand the smell and dirt of a fully uncatted system. If I get a catted midpipe, I will get an uncatted AMS DPs (or vice versa).
 

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This is the same debate I've been having with myself for over a month now. Decided I'd start with a midpipe and tune (picking a midpipe that will work well with additional mods if I choose to go that route). Figure I'd do this for a bit. If I want more later, I may pick up the AMS downpipes when I add a catback exhaust, but I will have at least one set of cats somewhere. I don't think I personally could stand the smell and dirt of a fully uncatted system. If I get a catted midpipe, I will get an uncatted AMS DPs (or vice versa).
With catless DP and catless MP it wouldn't pass mass inspection as well, no?
 

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With catless DP and catless MP it wouldn't pass mass inspection as well, no?
That is a risk, but I think you can mitigate that to a degree with good tuning. There must be some way to work around this as several members are running uncatted DPs and MPs. I still go back to the fact I don't like constantly smelling fumes or having to clean my bumper.
 
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