View Full Version : downpipe vs gutted cat?

07-10-2006, 03:23 PM
on my st185 ive got a fully gutted cat to a full mongoose system (2.5"). do reckon there is gonna be much point of fittin a 3" downpipe to the 2.5 system now or will the gutted cat have a similar result as the down pipe until i get a full 3" system. :squint:

07-10-2006, 06:47 PM
If the DP you want will bolt without modification to the exhaust you have, you lose nothing doing it now. If you have to modify it to fit the 2.5, then go back and change it for 3" later, it's definitely not worth it. The DP will be more efficient than the gutted cat, but the cat isn't going to be a huge enough bottleneck to warrant modding things once gutted. However, gutting the cat is not legal, and I didn't hear you say you did it :P

07-10-2006, 07:21 PM
uk.. baby...mines 1992 jap import.... guttin the cat is allowed b4 1993 regestered cars, then illegal from there after emissions law over here bit different .. :bigthumbu

07-10-2006, 07:24 PM
on a turbo car, bigger is better.

07-11-2006, 03:41 AM
KO Racing's Downpipe is 2.5".


07-11-2006, 05:30 AM
why not just take the cat off and weld straight or flexpipe instead? thats what i did to my gts and it sounded beautiful

07-11-2006, 11:26 AM
ko racing dp looks intresting, found a 3" dp for alot cheaper thou.

07-11-2006, 01:15 PM
Im in the same boat as "Hazee" here. my dp cat is already gutted and i'm thinking "is it worth it?"
The ebay 3" dp are going for about $150aus and a few of the guys in aust has had good results with them.
Also my turbo is an upgraded 50trim and i'm going to be running about 18-20psi through it soon.

Sorry to hijack mate. :)

but those results with the KO dp are pretty decent. about 6 more max power. 16 more torque, and it actually makes power all the way to redline! :rolleyes: :hyper:

07-11-2006, 01:51 PM
There was a big difference in boost response and my but dyno when I went from gutted cat to 3" Aussie DP. It is well worth it, and you are set up for future mods, unless a ct26 or ct20b or not part of your future. Then it is worth holding off for whatever turbo/dp combo you are looking to go to.

07-11-2006, 04:18 PM
Also if you guys are doing a full exhaust do the dp and a high flow cat. there are universal high flow cats out there and im sure they are available at a local exhaust shop. This way you get the performance you want while keepin the car emissions legal.

07-11-2006, 07:29 PM
The aussie system can be ordered with a high flow cat. It is done nicely to allow a "test pipe" to be inserted in its place in a matter of minutes. I have tried both, and with my current stock ct26, I can not notice any difference between the two.

07-12-2006, 03:11 AM
The high flow cat they sell is simply a Catco high flow that you can get here in the US.
Good kitty [cat]. :D

One problem I have with 2.5" dps is the lack of flow for the wastegate.
I don't know if a 3" ex will net more power than a 2.5" in regards to just the exhaust pipe size, but comparing a KO to a Aussie, the Aussie has WAY more flow for the wastegate....

Now if you had a dump pipe for the wg, or molded it better, :shrug:

07-12-2006, 04:53 AM
Word of wisdom on the downpipe. You get what you pay for.

Dont be a cheapass on your downpipe. Youre playing roulette. You will either get a good deal and it wont fit, or it will fit and it will break later on.

KOs downpipe seems to be the best one out there because Kris stands by his work.

07-12-2006, 05:08 AM
Personally, I'd like to see more aftermarket pipes with a full divorce on the wastegate, like the ones Berk did for MR2s, that way wastegate flow wouldn't be an issue, and neither would turbulance from the converging flows. Or at the very least one that rejoins the exhaust a good 12" down.

07-12-2006, 05:32 AM
Would it be possible to weld a pipe into the part of the flange/dp that is over the wg? You know, a DIY deal.

07-12-2006, 09:40 AM
Sounds like a dp is definately worth getting for people planning to stick with a ct2** turbo.

i'll probably get the ebay one. for the price factor + my brothers a welder, so i'll get him to go over the welds and make a support bracket ;)

07-12-2006, 04:21 PM
You guys who keep buying shitty ebay crap are doing harm to the aftermarket for our cars from GOOD companies.

Its not only the welds on these things that is an issue. Its the wastegate clearance. About 40 percent of them dont allow the wg to open properly and you get BAD boost creep until you port out the wg housing on the dp to allow it to open properly.

After buying the support bracket, and all the time spent fucking with it to get it to work right, its still the same price, or cheaper to just buy a real downpipe from a company that stands by their work. Im telling you guys, KOs is the way to go IMO.

07-12-2006, 04:59 PM
Lets add that some of the designs that are being mass produced were stolen from hard working folks (i.e some vendors on mr2oc). It was their hard work and skills that brought us most of the stuff we have for our cars, because we all know that the big companies can give a shit about us. The more you guys do this, the quicker you are going to put the guys out of business that deserve the sales. This is just my opinion. I don't want to start a big ebay chinese junk vs US again.

07-12-2006, 05:09 PM
just to add a line, berk tech will be releasing a new version of his DP next month, and from the inital pics, looks to be a MUCH better design than everything previous.
also, the guy VERY much so stands behind his work.
when i cracked my pipe, he offered a free replacement, and when i didnt like it, he paid to have my original pipe welded up and repolished.

07-12-2006, 08:05 PM
berk is an aweome company. he really backs up his products.

07-12-2006, 08:15 PM
Wish Top-End backed up their stuff like that! blah

07-12-2006, 08:15 PM
Is Berk a 6th gen thing, because I have never heard of him. Does he have a website?

07-12-2006, 09:56 PM
on a turbo car, bigger is better.
there are dyno's to prove "bigger is better" turbo or non.

07-12-2006, 10:15 PM
Is Berk a 6th gen thing, because I have never heard of him. Does he have a website?

No, Berk is an MR2 thing. They have a website.. but only make things in limited runs usually, so you have to watch the forums rather then the website.

07-12-2006, 11:00 PM
there are dyno's to prove "bigger is better" turbo or non.

Not true.

Bigger isnt always better on an NA car dude.

Theres the whole heat dissipation vs flow vs velocity thing on an NA car.

You have to maintain velocity, and to do that, you have to keep the heat dissipation from letting it all out at the source (so it has to hold heat in first). As it cools off it changes velocity. As it changes velocity it creates scavenging effect to pull the shit from the combustion chamber back through.

On an turbo car the turbo is always going to see more action than the exhaust, so it just needs to be able to take what the turbo sees. On an NA car, theres so much more to it.

07-13-2006, 01:03 AM

thats the site, but 90% of the products just get listed on the forums.

07-13-2006, 04:41 AM
I like the ko dp, looks like awesome quality, but its only 2.5", 3 would be better i think.

I couldnt find the dp listed on the berk site?what forum would it be listed on?

I still think the price difference is too high. the ebay ones go for 160$aus delivered, and i dont have the money to buy a ko or berk. otherwise i would.

I know these two company's make a much higher quality product, at a cost though. its a shame their designs were probably stolen, but that's what happens in business. maybe they should lower their prices to compete?, because you think they might go out of business due to the competition. I always try to support the smaller company's as much as possible. but at the end of the day i will buy what i think is best value. In my situation, money is the most deciding factor.I think i can buy a cheap dp,fix it up and make it work with a homemade bracket for much less than one that the other two company's are offering..

Anyway, i havnt made a decision yet. i'm still saving, planning and covering all my options. there's another dp for sale locally. Aussie 3" thats been hpc coated for around the $300mark. i will try and get that if i have the money in time.

sorry for the long post :)