ptrhahn

iTrader: (9)

Restrictor plates are silly IMO. I'd say there's a pretty good chance that exhaust flow slamming against the walls of piece of metal with a smaller diameter hole in it will flow like ****. Worse than a stock cat. Might just as well leave the thing on there. Unless you're going to hit a flow bench and accurately measure the flow vs. restriction characteristics of your restrictor plate to be sure you're not actually being counter productive (which, BTW would probably be more work than getting the turbo wategate ported), it's a crapshoot.

"go fast" parts are fun and all, but they cease to be "go fast" parts when you have to enact counter measures in order to use them. If you're tires aren't getting enough grip, why not throw some sandbags in the back?

Besides, as stated, '99's don't need restriction.

SiH

Whoa! Didn;t mean to start a flame war!
Sorry to any of you guys I may have offended by you thinking i was just ignoring advice - i wasn't!- I was just curious about the intricacies of either method - I was in no way disparaging any of the advice you had been kind enough to offer!
Some really good explanations of both approcahes here

Thanks all for your input, it's given me a lot to go over. At the end of the day, i guess there's only one way to find this out, so i'll mull over this info and decide what i'm going to do while i'm waiting for the car to turn up

Thanks again all!

[/humble Brit]!

DigDug

FWIW stock cat has a 2.25" restrictor in the flange.

I'm running 99s and got pretty bad boost creep when I went to a midpipe. First run in 3rd gear, it hit 14PSI at around 6.5K when I backed off, and it was still climbing at that point. It was fine until about 5.5K when it started to climb steadily. I'm tuned for 12PSI and use a Hallman MBC on the WG actuator to control boost.

I tried a few restrictor sizes and ended up with a 2-3/8". Any larger than that in colder weather and boost becomes uncontrollable at higher revs. Only slightly larger than the stock restrictor but without the catalyst brick.

In my case, I had an old clogging stock cat and bought a midpipe for less than $100 not thinking it would creep. Lesson learned there! My plan has been to run the restrictor until I get around to pulling the turbos, which given my motivation as of late, will probably be a ways off. Already been running it for two years.

Lately I've been thinking more and more about a metal substrate cat to try and keep the car emissions legal since it's a pain swapping cats to get it tested every two years. That's a better reason than any other to avoid a midpipe if you live somewhere with emissions.

matty

isnt logic a beautiful thing.

matty

dude no flame war. restrictor plates are dumb. people are getting advice in this thread. much better then the typical how do i make my stock bov make noise threads.