catless downpipe vs high-flow cat--thoughts and opinions wanted

[madbowler6]

hey guys,

so I installed the Milltek high-flow cat/downpipe on April 15. still running stock cat-back. the car sounds great and there's no CEL, but a day at the drag strip showed no discernible performance improvements (I run the DTUK box). so now I'm thinking I want to go catless.

my concern is the CEL. opinions seem to vary on the consequences of it. I've talked to a couple guys who say it's nothing more than a light on the dash. I've talked to another knowledgeable source who says he speculates the ECU does down-regulate engine power due to a catalyst efficiency CEL, though he couldn't be entirely sure.

does anyone know for sure, or have any hard data? obviously I'd prefer more power but I'm not looking forward to another downpipe swap job, and if I can drive around without a CEL and pass emissions with no worries, so much the better...but I'm not due for emissions until Jan 2020 so I've got some play time. I can live with a light on the dash but if I do, I'd like some real gains.

thoughts and opinions appreciated!

[madbowler6]

NOBODY has a catless downpipe with an opinion on it??

[electron bom]

ibu11et wrote a review about his experience

[-LoneStar-]

I can't really comment on your question but what did you run with the DTUK vs DTUK and Milltek DP? I see your in DFW ( as I am too) was it possibly the higher temps that effected you?

Also I would think the catted DP would still lead to gains. I know in the LSx crowd that I'm familiar with, catless vs catted was a only a 5-10 WHP difference.

What was the price for the Milltek? I would think being CEL free and the added sound (and hopefully power) would be worth it.

[madbowler6]

the weather was about 10 degrees warmer when I went back with the high-flow DP, but still pretty cool for this time of year in Texas. it was like 62 degrees or so. Unfortunately, I was running different fuel on the night as well...I'm estimating my octane level was probably around 98 on the night. so, not as apples-to-apples as I would've liked.

that said, the high-flow DP netted no discernible difference.

my buddy Nicotino who was there with me that night (also with a B9 S4) had the idea to say screw the tree, if you're after your best E/T and don't care about racing the guy next to you, just sit there and build boost til you're ready to go. I started using this technique on my last few passes and it chopped a couple tenths off my time. some of that effect might've been the higher octane fuel working its way into the fuel system, can't say for sure, but my best times of the night (all under 12.3) were using that method. only downside is it's pretty much impossible to race the guy on the line next to you unless he's willing to try to intricately coordinate staging with you.

I'm car 666 on these tickets (no, I didn't pick that number lol).[IMG][/IMG]