Hi need some recommendations for a high flow cat/downpipe---Bought this car used for my son, has aftermarket intercooler, alta catback exhaust, alta turbo pipes, k+n air filter/intake, alta stage 3 acessport tune, no cel and runs great, but would like to put a high flow cat in, any input/suggestions? also thinking about changing the k+n to an aem air intake. any suggestions? Thanks Brian

 

I have an Akrapovic high flow cat. This will cause a CEL unless your access port can get rid of it. It's pricey but used ones can usually be found on the Marketplace.

 

+1 for the Akra DP also, 100cpsi and sounds prrrrfect

 

For performance, just go catless. As the other said, even with a cat the Akra downpipe will throw a CEL. Just about any aftermarket downpipe will.

Also, AEM intake is great. But you likely won't see much difference over a K&N filter in the stock airbox.

 

i would stay away from the AEM intake ever thing is plastic
check out ddm works race intake.

 

I gotta agree with thebombardier --- my K & N Typhoon (plus a jillion more mods) took my WHP dyno reading to over 360. Just gotta be careful to not over-oil the filter when cleaning it.

Before going catless, ensure your local pollution regulations will allow that mod.

 

Thanks for the advice, the car has a K&N cone filter on it rite now, I was just concerned about all the hot air from the engine bay its sucking in. may be better off going with a jcw turbo and downpipe upgrade instead of a low flow cat. lots to consider, want to make more hp but keep the engine from grenading. I am a service tech with MB so I know you can only push these things so far before changing out some internals

 

I wouldn't underestimate them you can do some pretty cool things with him as long as you take care of them !! Don't listen to BMW service schedules ,

 

Yes lots of different parts available, have to add some catch cans and get the valves cleaned up, replacing the oil filter housing gasket and turbo feed line this week as well as reinstalling the carpets and interior, had to strip it out to dry it, get water leak fixed and fix all the electrical issues, its turned into a bit of a project but its a fun little car, my son really enjoys it and he wants to sink some $$$ into some performance parts, good thing dear ol dad is a tech. The cars I'm driving need some work too so I have to get this thing finished up. Got to get my 93 SL500 ready for the summer, jdm import with AMG body kit and wheels

 

Pro tip
Put the car into
Service mode

 

will do

 

If HP performance is the goal, and you're concerned about hot air, I suggest going with a good WMI system, like the Aquamist HFS4. I ran a 50 - 50 mix just for cooling / cleaning --- worked like a charm. With a little advance planning, you can get closer to 100% methanol for "special occasions". A good Manic tune, with three different new maps, plus a fourth (or base) map that can be your existing AP tune, gives you all kinds of options.

A bigger turbo and DP upgrade will help the engine "breathe" better, and is a good idea for an eventual upgrade, but a Manic tune with WMI will give measurable results --- just a Manic tune with an 80 - 20 mix bought me an added 15% WHP. Shop around for the closest manic dealer --- saves shipping the ECU.

 

AEM intake plastic is fine. I've been running it hard about a month and I've had no issues with melting/warping. It's really thick stuff. I don't even use the supplied heat shield either.

Plus, just judging from pics, the DDM intake looks like it doesn't use the cold air piping that comes from the grille, just the hood scoop. The AEM box uses both.

Yeah, this is another option too. Expensive, but a Water/Meth Injection system is the only sure-fire way to cool down your intake temps on these cars. Even with an AEM intake, and an aftermarket intercooler, on boost my temps will creep up to about 2-5 degrees above ambient in cold temperatures. I plan on doing a meth kit before the real heat of the summer.