hello everyone this is my first post. just got a dark blue 99 uk turbo. it allready has a scorpion backbox and centre section which i have to say sounds really nice, not too loud just a nice growl. first question is will the exhaust ive got now be giving any power gains? secondly what does everyone recomend on the air side. induction kit or just replacement panel filter? also what make is best in everyones opinion? k+N , Green etc. cheers

 

Panel filter, unfortunately you just missed a group buy on the STi filter which is reported to be the best.

 

so a panel filter is better than induction kit? if so why? sorry for all the questions. does a panel filter alter the sound in any way?

 

Induction kits only reap benefits when running serious big power mods, and then you need to sort out a cold air intake. Without that, it will just suck up hot air from the engine bay and may actually reduce power. The other downside is the excessive vibration can kill MAF sensors.
The better panel filters are the paper STi (non-cleanable so new one every service), JR Racing, Green and K&N. There have been many concerns over the ITG due to oil contamination of the MAF. A good free flowing filter gives a slight increase in airflow noise and may give a bhp or 2 (probably placebo) but the main reason is just 'cos it seams a good idea to let the engine breathe easily.

 

Thanks corradoboy, was about to type out a reply but you beat me to it

 

cheers fellas. so is an sti one better than a green or k+n? also does anyone know if the exhaust i have will be increasing bhp.

 

also, where do i get an sti one? and where is a good place to get a green or whatever?

 

scoobymania are due some STi panel filters in this week.

 

Exhaust will increase bhp. As it includes a centre I'm assuming that it's a straight through pipe, doing away with the original centre section which includes a cat. Therefore, should flow more freely. Possibly around 7bhp over std with the back box.

The Prodrive Performance Pack (an upgrade offered by dealers) includes a back box stamped Prodrive. I believe this is made by Scorpion.

 

The Scorpion exhaust will really come to life if/when you fit an aftermarket downpipe...........this is probably the most noticable mod that ive done to mine,(pound for pound)eg power gains,pops and bangs etc..

 

yep downpipe is the best mod as it removes a really restrictive cat, you could get up to about 12-15 bhp from this mod (depending on how good your engine and rest of the exhaust is). Sti panel filters regarded as good because they are more free flowing (apparently), and theyre a genuine Subaru part. Watch out on group buys, maybe another one coming up soon......

Mark

 

yes i think my centre section is a straight through. so what downpipe should i get and how much will it cost? is it then going to fail mot`s? cheers for replys by the way i think im going to like it here.

 

my backbox has scorpion stamped on it. forgot to ask how much louder the downpipe will make it? at the minute its not too loud until you open it up then it sounds top. dont really want a big annoying droning noise or anything.

 

Hear!, hear!, nice to hear sound advice and true commonsense. Move to the front of the class corradoboy. We see many cars with an induction kit fitted sucking in completely useless hot air. Then comes the trick mod !, " l'll take off the cover off the bonnet vent by the air intake". 'POP' there goes another MAF and another turbo boost valve.

AND some of these kits are fitted like this by "specialists" Hmmmmm, specialists in what? money extraction I think.

David API Engines / API Impreza

 

Hi there and welcome.

The my99 has a sensitive MAF and has been known to fail with non gen kits.

Try a search on this and you should find a lot on info on this.

FYI I ran an my99 with an Pipercross ind kit for 40K miles without any problems whatsoever - but others have had problems.

some kits are better than others at filtering out the cr@p.

I had mine fitted at the same time as removing the centre cat and a performance backbox. The car pulled much better through the gears and sounded great. Cannot say how much was attributed the the filter on its own but i really did notice the difference on mine.
Did i mention it sounded great

Try a search.

 

I think induction kits get unreasonable bad press. They do have advantages over the standard airbox, and some disadvantages. There seems to be a big misconception that because the cone takes air from under the bonnet its hot air, but a number of people, particularly Bob Rawle have shown beyond a doubt that once you are moving the difference between inlet temps at the MAF is only about 1-2 degrees C higher with an ind kit (see his thread in projects). Obviously, whilst stationary inlet temps will rise quicker with an ind kit than a airbox. Unless you fit a mounting bracket with your ind kit, vibration is an issue for early MY99/00 MAFs but this has been resolved with the replacement sensors now available. Water/dirt contamination will still break your MAF so get a cone that actually filters (sounds obvious I know, but the Blitz SUS are renowned for letting all sorts of crap into your engine), and don't remove the blanking plate (as David already states).

Another issue is that some kits offset the MAF voltage slightly, others majorly. This is due to the way the air enters the MAF housing (laminar flow causes larger offsets, because with the airbox the air "tips" into the housing, and mainly passes across the MAF sensor in the centre of the tube, whereas with longer inlet pipes and certain bell inlets a larger proportion of the air passes down the periphery of the housing , thereby missing the MAF). APS cold air kits cause huge offsets and can only be fitted safely with a remap, whereas the large cone K&N based kits sold by GGR and RCM cause small offsets. Small cone K&N 57i kits aren't supposed to cause any offset and are reportedly one of the safest to fit. A small offset is not always a bad thing because if the ecu is "seeing" a slighlty lower airflow and hence load, it will lean the fuelling and advance the ignition slightly thereby improving power.

Then there's the noise which is a matter of taste. If you want to hear a lot of induction roar, and your dumpvalve discharging, then an ind kit is the way forward. If you're looking for big power, again an ind kit is desirable but not essential.

I hope this has been of help to some of you.

Simon