anyone using catless DP and stock exhaust

[QTR FMS]

Hi,

im planning to buy catless downpipe and i was wondering how much louder would it be for a daily driver?

would it sound like a straight pipe or quiet-ish but raspy, and would it attract cops attention.

does the brand of the downpipe matter for fitment, flow and power? im thinking of getting VRSF as its the cheapest but not sure if i should go with AMS instead or something else.

regarding cel is it only light or does it causes throttle limiting or limp mode?

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[razorlab]

Louder than stock. Kinda raspy. Smells. Only CEL. Might trip limp mode on stock tune from overboosting.

 

[QTR FMS]

Louder than stock. Kinda raspy. Smells. Only CEL. Might trip limp mode on stock tune from overboosting.

how much louder than stock? like 5 decibals or more? would it turn heads on the street loud?

would you recommend catted over catless just based on sound level?

 

[razorlab]

how much louder than stock? like 5 decibals or more? would it turn heads on the street loud?

would you recommend catted over catless just based on sound level?

I have no idea decibel wise as I never measured it. I always put my car in normal mode whenever I see police and it's basically as quiet as stock unless you romp on it, which you wouldn't be doing in that situation.

If it helps, here are two of my videos. Exact same recording setup. One with GESI high flow cat and one with catless. Both OEM catback. Mic is in the battery box so out of wind noise and about 2 inches away from the left piping of the OEM catback.

GESI Catted:



Catless:

 

[MisterSkiz]

It sounds really good to be honest - its loud but the OEM exhaust mellows it out. Its the stink that I couldn't stand - and the fact that BM3 won't let you pass emissions with the CEL "tuned" off.

 

[razorlab]

It sounds really good to be honest - its loud but the OEM exhaust mellows it out. Its the stink that I couldn't stand - and the fact that BM3 won't let you pass emissions with the CEL "tuned" off.

Zero tuning software will do that at that level. They would get fined to the moon and back.

 

[MisterSkiz]

Zero tuning software will do that at that level. They would get fined to the moon and back.

They used to allow you to do it in BM3 by manually turning off certain codes - it appears they "went ahead and fixed the glitch, so it would work itself out naturally"

 

[djf]

Noticeably louder with the valves open but still very tame under ~4k rpms. Valves closed is still quiet. Not even as loud as the stock dp with valves open. Unless youre ready to tune the car I wouldnt go catless yet

 

[QTR FMS]

thanks guys this is what i wanted to hear i guess i will keep it on normal mode on the street.

is there any difference between brands that offers catless downpipe or are they all the same?

 

[jmikes]

It's louder but not overly so. Sounds much louder when you're in a garage or next to a wall (especially on cold start), but you don't hear the exhaust too much in the cabin while at 30+ unless you're full throttle flooring it.

The pops and bangs in sport mode get significantly more loud and noticeable, though. You're going to be making a lot of gunshot-bangs in sport mode without really trying. That's what I would be worried about in terms of pissing off the police with the noise.

Mine doesn't have seem to have much of a rasp to it (FI-Exhaust DP). It also doesn't typically get CEL's, although occasionally if I'm a little too heavy on the throttle before the engine is fully warmed up (4 bars on engine water temp gauge) it'll throw a code (I just clear it in JB4, and then if I let the engine heat up properly it doesn't come back no matter what I do)

With catless you'll definitely need to remember that it's going to make your exhaust smell, and you will be smelling it at a stop/idle if you have the windows down. It doesn't bother me as with an E-blend it doesn't smell that bad.

 

[Extreme Power House]

Dont have exact data but cold start is a lot louder , i'd say 50% easily
wide open throttle is also noticeably louder
regular driving, is 20% louder
you will get a CEL, fuel smell and its raspy

i personally prefer the catted option sound and lack of smell

 

[QTR FMS]

I just installed Mad Fat Boy 5" catless downpipe, it's surprisingly quiet, almost like stock.

It didn't throw a check engine light, but I only drove it for half an hour. The smell is worse than I expected, but I don't mind it.

It's overboosting and closing the throttle as expected, but I will fix that once femto releases the full unlock service.

I also took a quick idle decibel measurement in normal mode, it's between 73-74, and in sport mode, it's 75-76 decibels. I didn't measure stock, but I can't tell the difference in sound at idle.

 

[Extreme Power House]

I just installed Mad Fat Boy 5" catless downpipe, it's surprisingly quiet, almost like stock.

It didn't throw a check engine light, but I only drove it for half an hour. The smell is worse than I expected, but I don't mind it.

It's overboosting and closing the throttle as expected, but I will fix that once femto releases the full unlock service.

I also took a quick idle decibel measurement in normal mode, it's between 73-74, and in sport mode, it's 75-76 decibels. I didn't measure stock, but I can't tell the difference in sound at idle.

not sure how you can remove the highly restrictive stock cat and replace it with a catless downpipe and still not feel any difference. something does not add up.

makes me think that maybe you already had a catless downpipe on your car and do not know it

 

[QTR FMS]

not sure how you can remove the highly restrictive stock cat and replace it with a catless downpipe and still not feel any difference. something does not add up.

makes me think that maybe you already had a catless downpipe on your car and do not know it

I'm not saying I don't feel a difference, but you have to pay attention to notice the difference.

There is a small change in the exhaust tone and burbles, but it's not loud; it sounds stock, that is, with the exhaust valve closed.

The biggest change in sound is the rev match, it's much louder.

And yes, I checked the stock downpipe, and the was still in there.

 

[itzTang]

Are you trying to compare to catless + straight pipe? The oem exhaust still has a muffler

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