Mike Arias

I have a 991 Gt3rs, does anyone has experience eliminating or empting the catalic converter ? Do you gain any hp, and would you get a warning light .? Would you need to remap the ECU ?
Help appreciated...

Money2536

You will get a check engine light and most likely won't gain much if anything. You would need to compliment the decatting with proper header tube length/valved section/muffler combo.

This is what I have.

https://rennlist.com/forums/991-gt3-...-required.html

Charles@dundonmotorsports

If you just gut the stock cats there may be a slight power increase.

I would suggest our race header setup for your car instead. Check with 911_RS as he has a lot of seat time and comparison with his 991 RS.

Our DMS setup is tuned length headers and side connecting likes that keep stock flap function and it has NO drone.

rockitman

You will get a huge sound increase removing the cats and of course CEL. You can always buy one of these to get rid of the CEL. OBD2 port.

http://www.armytrix.com/CEL-Terminator.php

Mike Arias

I agree the best way is to install a exhaust system, appreciate feed back on different brands and which gives better hp gain and less weight, can the system be ordered without catalitic converters ? Thanks

Jamie@dundonmotorsports

The Dundon Motorsports Race system does not have Cats and adds 40whp to the 991 GT3 in our testing. Others have gotten more! On the RS we gained 20whp peak and 25-28max hp (on the road it seems to be far more than this).

Shoot me an email at Jamie at dundonmotorsports dot com

911_RS

IMHO: Cat delete is the way to go! BUT with the correct headers of course... So far I'm happy with my DMS system, it unleashed the full potential of the 991RS (w/out ecu tune) with just a simple bolt on headers. No cats, perfect fitment, way lighter than the OEM system, 321ss, beautiful cup car sound, no drone, better valves than the stock ones, no CEL so far on mine and the best part is... Plus 20whp peak 25whp max (feels definitely more especially when you go wot)

Other brands are also nice and will give you cup car sound don't get me wrong, but since you're looking for a catless system and seems you wanted to feel the full potential of the RS... Then this is your choice!

Karl911

Just buy a good catless race exhaust. If you have the $$ call Akrapovic

911_RS

Akrapovic doesn't have a catless system for the RS... Only the 100cell option.

Maxi_z

I think that akrapovic made a catless race version for some team or tuner that was a vendor on rennlist.

But probably the DMS makes more power so I would fit the DMS with maybe the akrapovic rear muffler if you want a muffler similar to oem but lighter and more refined.

HRE_Jurrian

Correct. The Evolution Race Line system will still have 100 cpsi sport cats that you see here:

Maxi_z

Correct the std akrapovic offer is only with the cat the one I saw was a custom race system made by akrapovic on request for bodymotion for the 997 gt3