Rasp developed after downpipe install

[SHO-TYM]

I ordered some catless downpipes from LMS, and had them put on. I still have all factory exhaust except for the downpipes. Around 4K RPM there is a rasp that has developed only in first and second gear. I was wondering if anyone else has run into this same issue.... I want to get a different catback system, but whatever I go with is going to just amplify the raspy sound. I had my 2 rear mufflers removed before the DP install and the rasp was unbearable,  so I had the factory mufflers put back on after the DP were installed, and that took about 80-85% of the raspy sound away.  just need opinions as to how I can fix the rasp so I can get a nice sounding catback system. Last thing I want is to spend $1,300 on a Corsa system just to have it sound like a Honda civic with a fart can.....

[SwampRat]

No way around it ....
non catted down pipes are going to be noisier ,think of the cats as mini mufflers of sort .

With the Corsa Catback added it WILL be very loud when ya put your foot in it.
At cruise mine had a deep tone to it that I personally loved ....
Not even close to being a ricer boy toy .

[SHO-TYM]

No way around it ....
non catted down pipes are going to be noisier ,think of the cats as mini mufflers of sort .

With the Corsa Catback added it WILL be very loud when ya put your foot in it.
At cruise mine had a deep tone to it that I personally loved ....
Not even close to being a ricer boy toy .

Kinda depressing to hear.... I don't mind loud when I get on the throttle.... but I DO NOT want to hear rasp.... sounds cheap to me.  I like a smooth tone while accelerating.  Maybe I could sell my Catless pipes and get some catted ones! Sounds like a lot of trouble.... but may be the way I need to go to acheive the results I am looking for.  I'd love to hear a Corsa system in person.... anyone near East Tennessee with Corsa?

[SHOdded]

Maybe a resonator like wasinger built would do the trick?

[SHO-TYM]

Maybe a resonator like wasinger built would do the trick?

That may do it.  I will talk to my exhaust guy here in town to see what he thinks about making something like that.

[Courier6]

I don't get any rasp with my PPE catted and Corsa exhaust, FYI.

[BiGMaC]

Much louder under acceleration ... But no rasp with my catted PPE DPs with AC on the in cabin rumble is cool too
When I was helping development of these also had non-catted on for awhile and no drone there... Of course I only drove about 80 miles with these and 3 dyno pulls.  Rest of exhaust is OEM.  Of course I don't hover the rpms at 4k and pass through it pretty quickly with hard acceleration and may not get there on easy acceleration... So maybe I just drive different.

[SwampRat]

Another possibility , are the LMS non catted downpipes made of thinner ss tubing than the PPE non catted  ones that I had ? This could make them resonate differently through various rpms.
Mine had NO rasp .

[ZSHO]

LMS tunes the car for catted DP,what about non catted DP?I know returning the vehicle to stock gave my car a more aggressive louder sound? Question is did SHO-TYM receive a new revised tune related to the catless DP?

[SHO-TYM]

LMS tunes the car for catted DP,what about non catted DP?I know returning the vehicle to stock gave my car a more aggressive louder sound? Question is did SHO-TYM receive a new revised tune related to the catless DP?

I just got the email saying that they sent me a revised tune. So I will be putting that on asap.

[BiGMaC]

LMS tunes the car for catted DP,what about non catted DP?I know returning the vehicle to stock gave my car a more aggressive louder sound? Question is did SHO-TYM receive a new revised tune related to the catless DP?

I just got the email saying that they sent me a revised tune. So I will be putting that on asap.

As I understand it the only difference in the tune for non-catted DPs is to turn off the second O2 sensor so you don't throw a DTC/CEL every time the engine is run.

[wasinger3000]

Maybe a resonator like wasinger built would do the trick?

That may do it.  I will talk to my exhaust guy here in town to see what he thinks about making something like that.

It needs to be within 1 inch to work properly. If you do go this route make sure you use the app I linked and find the frequency that you want eliminated.