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      09-12-2010, 08:26 PM   #23
Chako
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This makes sense in relation to scavenging effect. Lower torque in low RPMs, but higher up top when the exhaust pulse is quicker and scavenging effect is not as useful; where the free flow is quite important.

I think the tune is important to offset this, if you are going catless or HFC. The low down torque would probably be little to unnoticeable after tuning, and I have seen 30-40WHP gain after this is setup properly from stock. But warranty is important as well so it depends on your goals I suppose
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      09-14-2010, 09:22 AM   #24
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From a previous custom tune on stock x-pipe with rear section I made 366whp. Just by removing the primary cats from the stock X the baseline was 390whp. After slight dyno tuning of the same file to suit the primary cat afr (it went slightly rich) the car made 398whp. It was the most significant mod to date.
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      09-14-2010, 09:46 AM   #25
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Originally Posted by BT M3 View Post
From a previous custom tune on stock x-pipe with rear section I made 366whp. Just by removing the primary cats from the stock X the baseline was 390whp. After slight dyno tuning of the same file to suit the primary cat afr (it went slightly rich) the car made 398whp. It was the most significant mod to date.
Those are some impressive numbers
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      09-14-2010, 09:51 AM   #26
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A lot of this could be the fact the top end of the car is stronger with the HFCs and now that you went back to stock you lost some of that giving the impression the low end and midrange is better. I have yet to see a dyno in where there was a low end torque loss in the area under the curve that matters.

Its funny when I read about a torque loss at 3k rpm...first off check and see how often you are at this rpm when tooling around town. Also, keep in mind the OEM exhaust isn't that bad to begin with as it is allowing this 4.0L engine to make over 100hp/litre. The exhaust isn't even taxing this motor at this low rpm.
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      09-17-2010, 11:31 PM   #27
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J08M3 i actually do feel the difference in power with the hfc that i put from you bro! and seriously im the same like you i rarely feel the difference in these type of mods but this one i did. but it was noticable in the top end, i was actually very surprised! I like them a lot now that i got used to the loudness i feel it sounds awesome! and the car feels great talking about the power.
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      09-18-2010, 01:09 AM   #28
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sometimes, stock is just perfect.. even "7 different systems / combinations of exhaust systems" later stock is going to feel better. It's BMW and their knowledge vs. everyone out there that want to sell a mod'.
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      09-18-2010, 08:05 AM   #29
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Quote:
Originally Posted by ///M 4 Life View Post
J08M3 i actually do feel the difference in power with the hfc that i put from you bro! and seriously im the same like you i rarely feel the difference in these type of mods but this one i did. but it was noticable in the top end, i was actually very surprised! I like them a lot now that i got used to the loudness i feel it sounds awesome! and the car feels great talking about the power.
All I can say is the combo you got now sounded so sweet when you pulled away from Martino Auto Concepts. I'm glad you're happy with it and feel gains on your car. It sounded mean as hell as you drove off especially as it was uphill so there was a good load on the car.

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sometimes, stock is just perfect.. even "7 different systems / combinations of exhaust systems" later stock is going to feel better. It's BMW and their knowledge vs. everyone out there that want to sell a mod'.
I don't doubt for one minute the truth to the dynos showing more power at the top end and people feeling it. But I guess in my application since I only get to hit the high RPMs sometimes and most of my driving is street around town the OEM seems to bump the power or torque a bit at the low RPMs. The car seemed to have a sluggish spot down low with the pipes, but now it seems to be strong there. I'm sure I'd lose a drag race as the aftermarket exhaust should pull ahead as the RPMs get high, but I don't drag race so I don't care about a few .01 seconds or even .1 seconds.
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      09-30-2010, 11:51 PM   #30
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i agree, that is why the only software i ever get or would get is the Dinan one bc they do it right there at the dealer and it doesn't void the warranty. i would never ship my ecu off somewhere etc. awhile back a company was mailing it back with there logo stickered on there, nice huh. i think someone got there warranty voided when the dealer saw the sticker on there

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Originally Posted by J08M3 View Post
stock, wouldn't dare mess with the ECU for a couple of HP. and unless I was racing stop light to stop light that couple HP means very little. wouldn't risk voiding my warranty over that or want to deal with shipping ECU somewhere and then having to worry about doing it again if I should need some dealer updates that over writes my software.
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      09-30-2010, 11:56 PM   #31
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i don't doubt what you feel, but i know when i put on my midpipe my car had a boatload more tq and power below 4k then it did stock. pulling away the rear would want to rip loose with ease as when stock it def didn't do that. i know they claimed a small dip around 7k that most won't notice. i don't notice it. i got gains everywhere but for me where the midpipe made the most impression on me was down low where i felt stock it could use more.

hmm but if you like it thats all that matters. glad you finally got a combo you like

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So as many of you know I've had about 7 different systems / combinations of exhaust systems on my car. Now, hopefully my final and most recent combination is only an Akrapovic slip-on. I'm back to stock cats and xpipe, after just having the system combined with Fabspeed xpipe and HFC's. To be honest the car really seems to be faster now and must be making a little more torque in the lower RPMs (where on the street 95% of my time is spent). I say it seems faster cause I notice traction control kicking in all the time now as I accelerate cause the rear tires are trying to spin. This didn't happen nearly as often with aftermarket xpipe on. It's not due to loss of tread on rear tires as they are fairly new too. I'm thinking the full systems only really help you out at the very high RPM ranges and slow you down in the lower ones.
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