Shaqs77

Hi guys

my blob STi is going to RCM to have a new center pipe and downpipe fitted. Literally after that I’m going to Thwaites development racing for a power run and any tweaks it might need.

car is stock apart from the PPP


i quite like the idea of a full decat but at the same time I’d like to keep the car as original as possible and here lies my issue. Don’t know whether to go for a RCM decat down pipe or their catted version. I’m not planning on mapping it in the future.

what are your opinions? Car is loud now but what difference will it make if I decat it? Would motorway driving be horrible with the exhaust drone if there is any?

RockyRoad

Decat is such a pain for a road car and has very little if any benefit. Stick with a cat.

stamina_daddy

iTrader: (3)

Full decat is definitely a better driving experience but also a lot louder,seems more responsive.
I have full decat on a blob wagon no resonator in mid pipe.
But the milltek back box seems to stop any motorway drone.
I had a ninja 2 with same centre pipe and drone was terrible.
With most things you'll have to experiment with different back boxes etc to get to what you want.
I've literally had so many back boxes over the years from the 2nd hand market and love the milltek one.

Gambit

iTrader: (6)

Make sure you get the old ppp sportcat downpipe back from RCM they are worth decent money.


Just get a sport cat replacement fitted, decat is a waste of time on a road car and more hassle than worth for mot these days.

JDM_Stig

iTrader: (3)

Aftermaket downpipe with sports cat(so bell mouth off the turbo), and make sure the centre has a resonator box if you dont want the drone, most find the Prodrive/Scorpion too subtle, but I dont mind the level, makes track days easier as well if the db is sensible.

JdmSti2006

if You have ppp with sports cat and its working keep it ,its best of them all 100 cell high flow cat,it wont be much better with decat
do not mess with exhaust its never ending story after in my experience
i had rcm but jdm ver., very loud superbike sound i liked it but to loud on motorway and its made from thin steel,very light not sure thats good where milltek,prodrive and other are thicker

ST-X

Decats didn't have any impact on drone with my car when I first did it - to the degree that Andy Forrest questioned whether I'd done anything! That was with a standard centre and an STI back box. With the Prodrive box it was noticeably louder, and then with the straight centre even more so. With a prodrive cat in the DP now there's been no real change in the sound. Where your noise is tuned is predominantly in the silencers rather than the decats, after all they don't have any padding or baffles in them. That said I can imagine if you had an absolute straight system with no silencers then adding/subtracting cats would alter the tone if not the volume of your exhaust.