Well i dot have a plenum spacer Fia nd it made 9whp difference...maybe that is 15HP i dunno..i doubt since i got lightwheight flywheel...anyways maybe you are talkin about different psi numers...
IN ANY CASE the plenum spacer and testpipes are the best cheapest mods you can do

 

Not really. For 6 grand, you could get an APS single with APS exhaust. If you do install, you can easily be at 400 whp for a total of 6K bucks.


What other supporting boltons are you referring to?

 

not all fi comes complete. testpipe is a huge gainer. a lot of fi kits don't come with crank pulley, either, Exhaust is an obvious one and plenums and plenums spacers as well.

 

APS single bolted on with APS exhaust will get you near 400 whp. Nothing else is needed, not even test pipes

The one I installed had nothing but a UR crank pulley and the APS exhaust. The guy had under 6 grand into the setup and pulled 406 whp

 

And for another ~$350 put into test pipes and a plenum spacer, that 406 HP could very well approach 446 HP.
40HP would be a mod very well spent.

406 HP - stock @ ~240 HP = ~166 HP gained by the turbo.

Tubo = ($6000 / 166 HP) = $36.14/pony

FI Bolts = ($350 / 40 HP) = $8.75/pony

By any measure the FI bolts are a super deal!

Even if it is chalked up as ricer math at 1/2 the gains, its still a tremendous value.

And is safe to say (even under a worst case scenario) test pipes and a plenum mod can easily gain over 20 HP on a FI system.

 

ricer math all the way....
you dont have to do that tony to show you have a good product.. I am Fi and i have not seen an increase of more than 10whp with the spacer after many runs, but still its an excellent mod with great price, no need to resort to ricer math

 

one thing you are forgetting is that on a single turbo, you cannot use test pipes. Also, I have an aftermarket plenum, have seen spacers on FI, and would be surprised to see someone pull more than 10-15 hp out of one. That is the beauty of FI though, you just gained 150-200 hp, so who really cares about the extra 10 hp. The N/A guys will drool over a 10-15 hp component.

That said, with a tune, test pipes could alone add 40 hp to a TT setup

 

I'm not trying to sell or defend anything here. Just talking about what test pipes and plenum mods do. No rice, just the facts.

I don't know what happened in your situation but I know I've seen multiple independant pre/post polts of plenums and spacers showing no less than 17HP when FI. Three of them were insatalled while on the dyno and with nothing else changed.
The typical range is 18-24 HP.

They won't be easy to find, but they are posted here on MY350Z.

 

I'm not familiar with the APS single turbo setup, but yes, test pipes can make huge gains when FI. 40HP is very much worth the cost of the test pipe.

There are three members I recall that posted their FI spacer gains.
All of these were results measured without taking the car off the dyno.

ZBOY made ~17.5HP on a HKS SC @7 PSI
350ZNV made ~19.5HP on a JWT TT @7 PSI
RandysG made ~21HP on a Vortec SC @8 PSI

PM them for verification.

If their independant results are valid and typical (not rice) that puts the average plenum mod gains at just over 19HP.

If test pipes yeild 40HP when FI then the value is even better. (Lets not include the cost of a tune because most FI systems should be tuned anyways.)

With 59 HP gained for $350 on a FI system, there is no better value than this.