the dreaded exhaust question (again)

[Cloudsurfer]

Originally Posted by The Radium King

hi there, i'm asking the dreaded exhaust question (again). i've seached the forum but can't find what i'm looking for.

i'm new to the boxster and new to this forum - hello everyone ...

i have a 2000 boxster s. i am looking to increase power; i intend to do the chip/intake/plenum mods and was thinking about exhaust. sound is secondary and exhaust components (typically) expensive.

questions:

1) it makes sense to me that a freer-flowing exhuast will reduce torque at lower rpm (less back-pressure) but increase hp at higher rpms when more air is moving through; is this valid?

I'd say generally yes.

2) the boxster s has a more tuned exhaust, and aftermarket exhaust will yield a smaller (if any) hp increase; valid?

No, both cars use the same exhaust. 97-99 is one system, 00-02 is another, and 03-04 is different. Same from base to "S."

3) where is most power increase found - header, sport cats, test pipe (secondary cat delete) or muffler? i could see headers being most beneficial, as more power would be seen through efficiency (equal length pipes)?

Given how atrocious the stock headers are, I'd say the biggest gains are here.

4) if i am increasing/improving airflow at the intake with improvements to the intake and plenum, would these benefits be increased with a freer-flowing exhaust (more are in, more air out)?

Generally yes.

i quess i'm trying to drill down to whether exhaust mods are worthwile and, if so, which ones give the best bang for buck. and finally, whether a $76 ebay header is just as good as a $500 tuner header ...

Headers come in two varieties for these cars: "cheap" and "not cheap." Not cheap includes B&B, Supersprint, Cargraphic, Miltek, Tubi, FabSpeed, and a few others. Cheap includes the stuff on eBay for $100, and "discount" sites.

If you've ever wondered why good exhaust components cost so much, have a look at Burns Stainless (where most race teams and many exhaust manufacturers purchase components) and start pricing out what it takes to build a set of headers. Now add on R&D expenses, labor, and some mark-up so you can attempt to turn a profit, and there's your answer.

[jmatta]

Changing any of those items will likely yield little more than a lighter wallet. Most that have made the changes have only seen minimal HP gains, if any. If you wish to make your car quicker, you really have two options; increase displacement or lose mass.

Displacement is expensive, but so are add-ons that provide little payback...reducing weight is very cost effective, until you get into panel replacement.

[2K3_Boxster_S]

You can get 18hp if you do intake and full exhaust. see NHP exhaust thread.
Whether that's a minimal gain is dependent on what an individuals perception of expected results is compared to $$$ spent. It's not a cheap upgrade and it can't be done through ebay.

[Cloudsurfer]

Originally Posted by 2K3_Boxster_S

You can get 18hp if you do intake and full exhaust. see NHP exhaust thread.
Whether that's a minimal gain is dependent on what an individuals perception of expected results is compared to $$$ spent. It's not a cheap upgrade and it can't be done through ebay.

Hate to point it out to you, but the NHP is made in China "cheap" stuff.

[2K3_Boxster_S]

Originally Posted by Cloudsurfer

Hate to point it out to you, but the NHP is made in China "cheap" stuff.

Wrong. made in Canada. not even close to ebay cheap. Welds are beautiful, no fitment issues. China doesn't use T-304 stainless either. You got the wrong company.

[jmatta]

I think 18HP is pretty optimistic...there's no substitute for torque and you're not going to get appreciable increases with modifications. Gains will be at higher RPMs where it's mostly unused. I am not a technician, but have worked with my Porsche engine builder for years on track setups and know where dollars should or should not be spent.

[ekam]

NHP headers never look right in my eyes IMO, with the unequal length runners and side-entry high-flow cat. I've never seen any of the big companies use side-entry cats. You do get what you pay for really.