911mz

I am looking for some power gain here, some ppl said a set of fabspeed exhaust and header will give the most and some said having a header on would be useless if you don't uninstall the cat converter. Have any of you fellas out there have actually put these on as a set and dyno the car? Any suggestions would be great.

StuartFirm

IMO, headers are a waste if you don't upgrade everything down the line (cats and mufflers). I wouldn't remove the cats, just go to 200 cell Cats (100 cell throws a CEL for many people).

I like my Cargraphics (expensive, but worth it). Sorry, I do not have before and after dynos or weight savings. I just took a shotgun approach, since the car was 1700 miles away when I bought it.

Off topic, in your avatar, I seem to recognize the background did you buy your vehicle from Imagine Automotive Group/E-carlink.com? That is where my 986 came from.

911mz

yes you are saying set of exhaust, CEL anything else?

StuartFirm

Just depends on what you do. Rough idle and running could be an issue and if you remove too much backpressure, then you may actually lose power because the "scavenging effect" is not there. I'm not technical on this stuff, just have seat of the pants experience from running race exhaust and open headers on another vehicle. The car performed better with the race exhaust than the open headers.

911mz

so what do you think the recent post about Agency Power 13whp gain from exhaust and header which was currently done by vividracing on a 99 C2? how should we explain that?

StuartFirm

Explained with Mufflers, they are down the line. I would be interested in seeing the test run again with 200 cell cats added. I bet they would get another 3-5 whp. Also would be interesting to see just the headers with the bone stock cats and exhaust, bet it would only be 1-2 whp.

I'm gonna either get flamed or start a riot on this one, but I think the order of best bank-for-the-buck whp, pleasure & performance is:
1.) Cold-air intake.
2.) Low Restriction Mufflers.
3.) 200-cell Cats.
4.) GIAC or other software flash.
5.) Various Suspension/Brakes/Tire Upgrades.
5.) Supercharger/Turbo.
6.) Headers (I know this item is really a "while your in there" item that just sort of goes with #2 & #3, but if we are pinching pennies, I'd do it dead last).

Tbred911

cold air intake will let more HOT air in as well... so on a cool day it will work for you but on a warm day will work against you... the stock air box on a 996 is very consistant.

StuartFirm

True.
911mz, it's interesting to note that in the vividracing tests with Agency Power headers and mufflers in the other thread, the Torque fell off 2 lb/ft. after installing the headers. I would never have expected the headers to hurt torque. Can someone smarter than me explain this? I am just chalking it up to a slight difference b/w pulls, because I just can't imagine how headers and mufflers would have 2 lb/ft. less tq. than mufflers alone.