Magnaflow catback.
05-31-2009, 07:32 AM
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Magnaflow catback. I ran a 13.5@104 with only SLP lid with k&n. I have added a Magnaflow catback with cut out.
Are there any real gains with the cat back and what would be the difference between the exhaust and the cut out being opened?
Are there any real gains with the cat back and what would be the difference between the exhaust and the cut out being opened?
05-31-2009, 07:42 AM
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You will probably pickup around 15-20 rwhp. I say if you're running an auto you will drop 2 tenths, if a 6 speed maybe the same due to less traction with the new mods. Good Luck
05-31-2009, 09:30 AM
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Im wondering with the cut out open will I see an increase in my mph over the ET?
Does my trap speed seem low to any of you? I know the 13.5 is about average.
1 more thing. I had my 18's on when I ran the 13.5@104... They seem to be about the same hieght as the stocks because the 18's have a low profile tire.
Does my trap speed seem low to any of you? I know the 13.5 is about average.
1 more thing. I had my 18's on when I ran the 13.5@104... They seem to be about the same hieght as the stocks because the 18's have a low profile tire.
05-31-2009, 09:48 AM
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Well without knowing whether you are A4 or M6 it's hard to answer. That trap seems about average for an auto with your mods. Your et seems like it could be improved some (what was your sixty foot?). With these cars and even a few mods it seems that mid thirteens are sort of a "baseline" and there is usually room for improvement with driver mod/more seat time. As far as a cutout goes, sometimes you only pick up a few ponies if you have a particularly good flowing cat. With a magnaflow, I'm going to hazard a guess and say that it would net you about 10 rwhp (15 with cutout open). Hope this helps and good luck.
05-31-2009, 12:54 PM
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Well you sound like you are on streets so I guess you're doing ok for your sixty. I'm not sure how those 18s work out though? Does your car have the 273 gears? I have the 323s but if you have the 273s you might want to consider the 373s, it would yeild a nice reduction in et. I would myself but it won't be as noticeable for me and my current gears. It would still benefit me but in my case I think my money would be better spent elsewhere (like towards a stall maybe?) Either way have fun with it, and yes a catback is a good idea and so is a cutout. You'll have more power and better sound 
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05-31-2009, 01:18 PM
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i have a similar set up i have a single cut out right after the cats wear they meet i ran a 13.8 with them open and a 13.5 closed i also have an a4 i think these motors like a lil back pressure.
05-31-2009, 01:26 PM
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but i also noticed a good pick up in top end when i opened them around 80mph (electric valve cutout) so i think the reason u feel a lil quicker closed is the lose of low end torque with them opened
05-31-2009, 01:56 PM
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biggest thing hurting you is those 18's, its not about the diameter of the wheel/tire combo, its about the weight, and 18's with low profile is going to have a greater moment of inertia (more resistance to change, thus slowing you down) than 16's with a taller tire. I bet you'd pick up about 3 mph on the top end with 16's. oh and the cutout should give you power throughout the rev range, dont go by SOTP feel, get it dynoed with it closed and opened... you'll see 
05-31-2009, 05:22 PM
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biggest thing hurting you is those 18's, its not about the diameter of the wheel/tire combo, its about the weight, and 18's with low profile is going to have a greater moment of inertia (more resistance to change, thus slowing you down) than 16's with a taller tire. I bet you'd pick up about 3 mph on the top end with 16's. oh and the cutout should give you power throughout the rev range, dont go by SOTP feel, get it dynoed with it closed and opened... you'll see
Interesting. I want to trap as high as possible. I will throw my stocks back on before next track visit. I havent been to the track since catback was installed.
06-02-2009, 05:53 PM
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yea i think the cutout can mess with the tune, a ran with a catback off and the car seriously felt about 3 tenths slower, however i have also heard that cutouts will pick up a couple horse over a an aftermarket cat back, so dk if that helps but just thought id throw it out there
06-07-2009, 10:42 PM
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i can go with that, unless the car is dyno tuned with a catback on, i think that may be a different cenario.....true? false? any opinions? facts?