Stock headers compared to......

[Benny771]

Are the Headers on a 89 930 USA car restrictive compared to Fabspeed or others?
What do you the think the "proven" gain would be in HP?

[alwaysflat6s]

The "headers" on a USA 89 930 are basically 930 ROW. They breathe reasonably well on a stock engine and are far superior to early 930 USA units. The ugly restriction is the very restrictive factory USA cat/muffler setup [which you may or may not have in Canada].

Unless you are modding the engine you are spending a lot and gaining very little with aftermarket headers. If your laws will allow, your best bet is unbolting that awful cat/muffler setup [but saving it if you need it for emissions tests or if a future owner is dumb enough to want to install it again]. Then find a good muffler. even a stock factory ROW muffler will make you feel like you have gained a lot of power. Plenty of aftermarket mufflers and you can do a search of this site for opinions on these. Some are sweet, some are very loud, some area fairly quiet. Your choice and your opinion. Some guys even run straight pipes and might even be somewhat reasonable as long as your power output is modest enough [no way around it. hp = noise].
GL & have fun.
JR

[Miguel Antonett]

A world of difference including the mufler... I'd say between 10 and 30 hp increase... you'll get a well sorted amount of answers on this one.

[RarlyL8]

I can offer some facts as we have dynoed about every system out there.

The '86-'89 USA heat exchangers and J-pipe are the same design as the '78-'85 Euro exhaust. The mufflers are different with the Euro edging out the cat/muffler combo of the USA by about 5WHP.




A lot of testing was done on my mule engine which was Euro spec with SC cams, short neck 1/2 bay IC, and K27-7200 turbo. With the stock Euro muffler that engine put down 300WHP consistantly at stock boost level.

> Muffler change to our single outlet street muffler +12WHP
> Muffler change to Zork Tube +15WHP
> Stock Heat Exchangers change to Short Tube Headers +35WHP
> Stock Heat Exchangers change to Equal Length Tuned Headers +50WHP

Do not forget the boost threshold reduction supplied by headers. Headers and muffler alone will reduce 3LDZ boost threshold by 1000rpm.

[oilonly]

I replaced the muffler first with RarlyL8's dual out and noticed a large difference in power. Then purchased a set of short tube headers and even more power. I have no idea how much horsepower I gained but the car is much faster with headers and proper muffler.

[jsveb]

I just installed the zork instead of my Borla. I believe I can see boost onset is sooner and also it seems to run a bit leaner at cruiser which I guess could be attributed to lower back pressure.

This has not been logged, so it is not conclusive, simply 40 minutes driving impressions. I wonder what a set of Brian's headers would feel like...? $$$

[JFairman]

Your question has been answered thoughly so I wanted to say your stuff looks nice and clean.

If you want to easily clean off the cosmoline overspray thats making the brown color on your trailing arms get some brush on or spray on paint remover from home depot or wherever and spray or brush some on the trailing arms and wait 10 minutes.

Then you can hose it off and they look like nice clean cast aluminum afterwards.
If any of it is stubborn and is still hanging around spray on some more after they're dry and scrub it a little and wipe it off and hose it to finish it off.

If you have painted wheels remove them first do they don't get messed up.

I think it's worth the effort when the bottom of the motor and transaxle looks as nice as yours.

edit: wooops I just realized Brian posted that picture... oh well, take what I posted fwiw.

[RarlyL8]

Sorry for the confusion Jim, I used that picture to demonstrate what the exhaust system in question looks like. Yes I agree that undercarriage looks nice and cleaned up would look fantastic!

[Benny771]

Thank you all for the replies