How much HP get an xa with the header???? How much Hp I get if I install an aluminium pulley???

 

the mfr will usually list hp claims.
remember this is usually if the part is the ONLY upgrade.
in a package (header, exhaust, intake) the gains are smaller as a total

ex: header claims 10hp
intake claims 10hp
muffler claims 10hp

you might only gain 15 or 20 hp.

 

Any headers to recommend?

 

well you got DC 4-1, OBX 4-2-1, MMW 4-2-1, TRD 4-2-1

depends on how much you wanna spend

 

aren't all the header out there for our cars just 4-1? I thought I remember someone saying that before. I may be wrong.

 

You're wrong. Most of them are 4-1, however, OBX and MMW make a 4-2-1... (good luck getting your hands on a TRD one)

Supposedly, DC has a 4-2-1 in development.

I have the MMW and I really love it.

 

performance wise..
what's the difference between the 4-1 and the 4-2-1?

 

You'll see better low/mid gains with a 4-2-1 and better high end gains with a 4-1.

 

oooh. cool. thanks
one more question (don't mean to thread jack or anything =x)

but it'd still be okay to get headers without an exhaust right?
is it going to sound ricey that way?

 

you'll be fine if you didn't get a free flowing muffler

 

would it still be okay with the stock exhaust?

 

Yea, it'll be okay, but you'll see better potential with an exhaust too.

 

don't mean to thread jack either, but how much of a difference is there between ceramic and stainless steel headers

 

Ceramic coated would radiate less heat than the Stainless, although I haven't really seen an issue with my stainless one (and I removed the heatshield) The MMW stainless header has brackets for the heatshield... others, like Strup and OBX don't.

The only real concern with stainless is if you have a manual trans, since the shifter cable runs very close to the header and some have had it melt the cable insulation...

 

I have the Strup, there's lotsa space behind it on the xB so heat buildup really isn't an issue; not real sure on the xA. Ceramic may offer better performance since it will suck more heat away from the engine, keep less of a temperature gradient in the header and possibly increase laminar flow, this is why people Jet Hot coat their headers. I never had rasp with the header, but coupled with a high flow exhaust it will produce a constant drone at cruising 45-65 MPH, 2800-3200 RPM. Ened up having to use a silencer to cut it back, went with the active tail one from Apexi so I didn't lose performance.

 

How much was that Apexi active silencer? Work well?

 

Not that cheap, around 130 I think. Before it I had the Apexi Super Silencer but I had sheared the bolt off and it fell out somewhere on the interstate. The active tail silencer seems to be quieter and doesn't vibrate in the tail pipe like the super silencer did. It does seem to still run rich when not under load due to the increased back pressure, but when it opens up the power still feels there. I wasn't able to get it dyno'd since the shop needed to remove it to get an AF/R reading. I need to get the UEGO AF/R installed so I can really see how much the tune changes with it in.

I've also been thinking about putting a lighter spring in the valve mechanism, I think it was made for a car with a larger engine and probably more force to open the spring up. The whole unit can be disassembled so it would just be a matter of taking it apart, measuring the spring, weighting it and getting a displacement to figure out the strength, then buying a ligher one of the same dimensions.

 

You're F/I and it still doesn't open that well?? Guess an N/A box would have no chance.

 

I really have no clue when it opens up. It gets a lot louder when I step on the gas so that's one indication. Also, when closed, it runs slightly rich with the tC injectors, so carbon builds up. When the gas is pressed, it gets blown out the sides when the valve opens, so I know air is bypassing the silencer tube. The main thing is I don't know when it starts to open or how much it opens since I can't push the gas and look at the tailpipe. I suppose I could get someone else to rev it or have a mirror set up. I really just want to play with the spring rates and see if there is a difference since it is able to be taken apart and springs are cheap.

I do pull it out and polish it at shows for display, but I'm still always worried someone might steal it. Hasn't happened yet and we park as a group so someone's always there next to the cars.