Saw a thread about the benefits of a breather filter stating it resulted in better throttle response and a fuel efficiency increase of 10-15%. I was wondering if anyone else has done this and if they've felt a difference. Also I assume you can just get a universal one off ebay and it fits right on?

Hello AKS,
From your 3 posts this morning I'd say you are having some performance problems with your 323F.
It's extremely unlikely that any relatively small 3rd party non-Mazda approved modification would give a 15% benefit in anything (fuel efficiency, performance, or anything else). You'd need a huge change to get that benefit.
If you're looking at a non-standard Cat, filter and intake resonator then I'd say have you checked the standard fittings first?! The BA (1.5 I think you have?) does get its air systems bunged up, it's normal. I made a significant difference to mine by (1) taping up the large intake pipe (between air filter and throttle body - it gets cracked easily); (2) putting in a new air filter; (3) whist the pipe was off I squirted carb cleaner into the throttle body, you wouldn't believe how black it was inside! The idle control valve needs similar treatment (and the inlet manifold maybe, but that's a bigger job, because you need to dismantle a few bits to get inside that); (4) check (and replace) the PCV system and pipes; (5) make sure all the rubber pipes around the throttle body are pushed on correctly and in place.
Then replace the spark plugs with 4-electrode or platinum ones.
Then change the oil filter and oil with 10W-40 or 5W-30 or similar, proper stuff not supermarket brand!

Then go for a drive, check for leaks.
Then go for a blast. You'll enjoy it so much more. Think of all the Euros you've saved by not buying after-market expensive stuff that doesn't really do much.

I'm not really having any performance problems on my 1.5. It's in very good condition I'd say. I'm just looking at ways how to increase performance somewhat you could say, get better throttle response and such, and those posts I made were possibilities that I found. I cleaned up my throttle body just a couple days ago and the cloth came out black but it made a nice difference in throttle response and power delivery, smoother all around. I noticed that the pipe between the throttle body and the intake is starting to crack if I bend it so I might get aluminium tape and take it up but it doesn't seem to leak. I have a k&n panel filter in it which I got back in the beginning of the year and it made a nice difference. I haven't touched the idle air control valve yet or the PCV pipes.
I was considering upgrading to iridium plugs also.

What do you mean exactly by the standard fittings regarding the cat?

Hi AKS,
I was referring to your other post about a magnaflow cat, and suggesting that maybe the original one needs checking first that it's not bunged up or something, before you try a different one.

I appreciate that some owners want more power from the 1.5, but there are limited ways you can do this without spending a fortune. Other modders on here will have some ideas, but Mazda made a well-balanced mid-range engine, and it drives very well for what it is. For my own I'm not a modder and I have concentrated on making it work like it was originally intended to!

I haven't checked my cat yet although I suspect it's probably fine as my BA only have 64k km on it and was always taken care of by the previous owners. I was just wondering if maybe a magnaflow cat would help power a tiny bit and change the noise but I probably won't touch the cat, at least for now. I do have other mods in mind to make the car abit more fun and responsive but when it comes to power there really isn't much you can do without spending a fortune
You should keep an eye out on my thread about my car to keep up with what'll be going on.

Hi ArtistKS, may i ask about your age? Not here to offend you, i'm just like you (trying to squeeze everything the 1.5 has) but from experience i'll tell you:
Just drive your 1.5 as it is!
Otherwise you are looking to alot more money spending than changing an exhaust or cat or something other small part so you can make more power from the engine.
Yes, everything you change on engine do make a difference, small but it makes it.When you combine some mods with others the difference is bigger, but in this 1.5 the base you are going from is so small that every modification/upgrade couldn't be even felt from a "regular" driver.
Just for comparision:
if you have car with 90HP and alot power modifications, lets say you have increased the power with 10 to 15%
this will give you what, 104HP, small gain in power for alot of cash,time and effort. (14hp increase)
If you have car with let say 150HP as a base the same mods in percentage (10-15) gives more end power output just because the base is much bigger. => 174hp (24hp increase)
Lets not talk about turbo setups, there the power is much easily achieved.
Soo if you have some money to throw at your ride, do it, im not here to discourage you, but you will end up with not that what you've expected.Talking from exp. here again.
I've slid that road and it's all downhill i tell you.The further you go, the steeper it gets.