I'm going to buy one for the stock airbox but dont know if it's worth it. So, does the K&N filter work a lot better? How much HP does it add?

 

doesn't really add HP..the stock box is still restrictive..what it will do is throttle response very slighty..

 

I heard it adds ~10 HP.

 

I'd say 2-3 max...I think 10 is wishful thinking....

 

the filter in a good airbox (other than the fd) could add 10-20 hp...
you got to realise how small a hole the stock air intake is pulling through..its like removing a paper filter from over a straw....then fact remains your still breathing through a straw

 

The stock box is actually pretty big size. Its inlet duct is a bit small. I am thinking of drilling some holes on the bottom to get more hp.

I don't think too highly of the K&N drop in. HP gain is negligible. I don't like the fact that it doesn't have the platic frame around the stock filter. K&N only has the rubber gasket and it could deform/fold under suction. The K&N definitely doesn't filter as well. When I hold it up to a light, it's more see thru then stock.

I think even if you just drill a couple of holes under the box using a stock filter will yield better results than a drop in w/o drilling a hole.

 

I wouldn't look to air filters to increase performance too much...that kind of thinking is slightly leaning towards riceboy thinking

 

K&N doesn't filter very well? Uh...it's not the best-selling widest known aftermarket filter company out there for nothing. Actually, K&N filters have been shown to give several hp on the dyno where others have failed (on other cars, never seen a test on an RX7). A K&N filter certaintly couldn't hurt your car. You have nothing to lose in trying one. Just because you can see through it doesn't mean it's not filtering.

 

yup oiled cotton filters better than paper

theres tests on it...

you cant see through foam as easy as k&n but they filter like ****


put it in and see what happens..personally id make some extra inlets like the rob rionetti way and duct them to get soem more fresh air in there

 

I used to have the RB air-inlet with K&N drop in - worked pretty well - definitely better than stock - the stock box actually is one of the best for intake temps - seen it on the scuderia site. If upgrading an IC you'd have to use a Greddy or Blitz smic with the RB w/ K&N - lot's of people are doing this with great results - I'm sure both together are worth 8-10 rwhp - definitely makes your turbos louder - cheap hp.

 

I used to have respect for K&N until they started advertising on TV that you should buy their filter instead of paying up to 1000 for a new exhaust or 2000 for a tubo kit. Do they really think that I would be satisfyed by the best case scenerio of 20 HP out of a Camaro if what I really wanted was a turbo kit hoping for another 200 HP? I think I will just stick with my Fram until they come up with a different TV ad. It is almost sad how much advertising affects my purchasing decisions

 

What's RB air inlet and how much does it cost? Can I get it with the K&N filter (I dont have an upgraded intercooler)?

 

http://www.racingbeat.com/FRmazda3.htm

It still draws hot air back through the intercooler, just like the stock air box. In fact, I've heard it makes that problem worse. The Rob Robinette type air box mod looks like the best of the "cheap" solutions I've seen so far.

 

I have one thing to say about the K&N cone filters..... They like to melt in my engine bay

 

M....m...mmmmmelt?!

 

I've seen dyno testing between components and open intakes provide a lot more hp gains than exhaust. Stock airboxes are very restrictive.

The gains on a Supra TT was around 20-25 while the catback only provided around 10-15. Downpipe provided a litt more than then exhaust. I think people who modify the catback before anything else for performance has a little riceboy in them that wants some loud noise.