So a local has given me the option to buy brand new HKS downpipe for around $150. And having read that this a needed mod for lowering underhood temps, i am considering getting it.

My only concern is if my stock ECU can handle it? I have tried reading and searching but ended up inconclusive. The car is completly stock except a Remus catback exhaust.

What should i do?

 

Either way you could get it and just put a restrictor plate between the flange of the downpipe & the rest of the exhaust if it creates a boost problem.

That way, you will still lower under hood temps and not boost ceep

 

If you still have stock intake, intercooler, stock main cat, you should not creep at all. Just a downpipe and catback exhaust has been done many times without hiccup.

 

I can second that as well. I'm completely stock except for an HKS downpipe. No boost issues.

 

All I have is a Downpipe car runs great and no problems so far.

 

We install the HKS downpipe as a reliability mod on stock ECU cars all the time. No issues and a little bump in power.

 

Just to add a little onto this, would there be any issues with other downpipes such as Pettit or Bonez assuming everything else is stock? I've read that the HKS is slightly more restrictive compared to other downpipes but probably not enough to make a difference?

 

A downpipe is a downpipe. With all other stock components in place the difference between down pipes will never be noticeable. The point is to eliminate the precat. With a downpipe, you'll be fine. Anymore than that, and you're gonna have severe spiking and elevated boost issues. Keep it simple.

 

No they're not. A good dp has thick flanges, good welds, properly positioned O2 bung and the tab for the transmission mounting bracket. Not all of them do. And HKS is designed for a RHD car. If the OP has one, that's great. Otherwise you could argue they are, somewhat, more restrictive. Regardless I'd take it over some of the cheezy ones I've seen out there.
And no issues with creep even on a non-ported twins wastegate as long as you keep a cat. Even a hi-flow cat. A dp isn't even in the equation IMO.
As Banzai mentioned, it's a reliability mod, removing the danger from the restrictive, and stupidly hot stock pre-cat. Especially if the OP opts for heat-coating it or, at the least, header wrapping it before installation.
No experience with Pettit, but I've got a Bonez that's over 12 yrs old with absolutely no complaints.

 

Thanks all it pretty mich confirms what i figured out reading the post i found when searching.

Also, i consider the HKS a temp fix, since i plan to go full SMB stainless exhaust at some point, but i wanted to get rid of the stock one of the ecu could handle it. (Owning a rotary is scary lol)

The HKS is already in the country, going cheap, and ill wrap it before installing ig i buy it! Any prefs on wrap, or will all work well? Also, is there any coating i can apply myself?

Thanks for the help!

 

Its not a 15 minute job to install a downpipe. Its not something you want to swap if you don't need to.
Why not just install the one you want now? Every car is different so make sure you have a boost gauge to verify you're at 10. The previous owner could have hollowed out your main cat and your motor would be gone the first time you boost. Also I don't know whats up with these other guys but with an intake dp and catback I was boosting to 12 psi on cold days in FL.
You should also get an intake now to compete the flow mods. Don't use a restrictor plate to undo performance gains just get a boost controller to keep it to 10. You won't have creep with these 3 mods, only spike perhaps with cooler weather. Its been proven you can throw any mod on stock ecu totally safe as long as you regulate to 10psi. Only mod you can't install is a midpipe because boost creep will exist unless you remove turbos to port wastegate first. On wrap or paint make sure to use quality material or it will make a mess or cause a hazard. Exhaust manifolds and downpipes glow to the point of looking see through when boosting aggressively

 

Simply bevause i cant afford to priority the one i want i grt the HKS for cheap, and it will work as a reliability mod from what poeple here say, and that should be enough for a while.

Its a 30k miles car, completly stock except the catback, and i wont touch the engine for a while yet