purrybonker

A search reveals lots of pro/con, or at least pro/neutral on the x51's. Most recent discussion in 2008 indicates a number of people were considering or planning on having it done.

What are the results? Is it worthwhile?

kdurg

It's no secret the 997s ability to breathe can be enhanced. The stock header design, IMO, is awful. The X51 units open the car up a bit in the mid range and offers a throatier tone especially when combined with PSE. I wouldn't expect much of a hp increase though. Swap out your cats with 200cell offerings if this is your goal.....

If you're into DIY projects, this one is quite simple and can be done in an hour or two. Be careful of the disconnect at the cats---at least on my '05 the 3 point flange had studs and a few snapped when too much torque was applied to loosen the nuts.

The following pics courtesy of Edgy01 ( Dan ) illustrates the different designs.

Relatively inexpensive around $700 compared to aftermarket pieces. Most here will tell you this mod is a go !

mdrums

Get a set of long tube tuned headers with a F1 style merge collector. Couple these with 200 cell cats and free flowing mufflers and a free flowing intake plus a porperly tuned ECU and you will notice a little bit more performance.

Para82

Kdurg- would love to hear a youtube video of your setup when you get time, thanks.

Edgy01

I still like mine. (X51)

Dave07997S

At best there maybe just 2-3hp difference between the X51 and a full length header. The money you save can go toward the real hp maker and that is the 200cpi HJS cats. Even AWE with their full system saw only 7rwhp after they installed the cats and mufflers. From what I have seen X51 headers by themselves add maybe 5rwhp but strengthen the midrange a tad. Save the money with the X51s and get some cats to go along with it.

Dave

RonCT

You really need the "works" to make it worthwhile. I experimented with many variants and in the end, the most cost effective combination that gave real gains was: X51 headers, AWE Cats, Softronic. Kept the stock mufflers. The headers and cats gave the car a great sound and Softronic helped to manage the lower restriction.

KeninBlaine

I put X51 header, PSE, and AWE 200 cell cats on my car. While I love the sound, it is my opinion that the combo doesn't actually make any measurable difference in performance. I used a g-tech device on my car, and it measured 292 NET RWHP, which is in line with others who have used this device on cars with stock exhausts. It appears that the headers, mufflers, and cats only improve performance on cars with forced induction. To me, spending a lot of money on exhaust systems with the hope of gaining measurable power, is a waste of money. Put the money into driving lessons and good track tires if you want better performance. For more measurable power, get a supercharger.

Para82

Anyone on Rennlist have a supercharged 997S?

RonCT

Kevin - as mentioned in my post it's all wasted if you don't update your engine management software to work with the lower restriction in the headers and cats. I don't remember exactly, but I'd say the gain was about 30 on my 997.1 w/ X51, AWE 200 cats, and stock mufflers. Bonus: The sound was intoxicating with people on the street and track coming over asking what I had "under the hood".

NVRANUF

+1


I ended up using AWE headers and 200 cell cats with the stock muffler cans, and IMO it gave the best sound.

The AWE cans added absolutely nothing sound or performance -wise!

Quite a difference in stock vs AWE headers:


Also a big difference in sport cat vs stock:

Seal

X51 headers with PSE rocks!

awilks

see multiple previous posts I have made discussing the Farnbacher Loles Power Plus package I did to my 07 C4S. I did a lot of research before deciding on spending $10k on mods: X51 carbon intake, full exhaust system (incl 200 cells) and fully reversible ECU flash all dialed in on their dyno. just over +30hp boost, and just under +40ft lb torque. Those #'s, especially the torque increase, are much better than the X51 from factory. Have had mods for 10k trouble-free miles now, and could not be happier about the improved engine response, torque, and very strong pull now in right up to the redline. They are in CT so maybe not applicable outside of New England region. Most people who spent extra $ on the X-51 option, who have posted in the past, are satisfied with it. There was a good post a year or so again from a guy who had X-51 and took his car to the track with a friend with non X51 otherwise same spec C2S...to paraphrase he was underwhelmed with the fact he could not pull on the non X-51 car in any meaningful way, and thought it should have been more discernible. Reviews including Excellence have noting the improved throttle response, and freeing revving nature of X-51 motor but 23hp and less than 20ft lb's of torque improvement are not that noticeable behind the wheel. There are some good deals on used GT3's which would be best way to move up the performance and handling curve.

Edgy01

One of the guys in my car group has a s/c 997 C4S.

It's been a nightmare. Very NOT ready for prime time kit.

964RS_NGT

1Gunner,

Can't see your pictures.