No i think my exhaust has broken in now that im about to go past 4k rpm (oil consumption issue). Its starting to tame its self to my likings.

Im going to take her off the market

 

haters! That's probably not restricting flow at higher rpms as much as you would think and if it was totally flush there wouldnt be any flow into the crossover pipe at lower rpms where you gain torque from the h-pipe... and not only is it the best looking exhaust it's the best sounding so stick it.

 

thats obvious restriction, halving the diameter of the pipe by creating a bottleneck isn't helping anything out.

h-pipe is made to smooth the flow by filling in the gaps between engine pulses from side to side and keep constant pressure on the flow so exhaust can escape faster.

 

Also-exhaust restriction=back pressure :P

 

back pressure is never a good thing.

exhaust scavenging is what you want. Basically each pulse goes down the pipe in a way that causes a vacuum that pull exhaust out for the next pulse. this is why people play around with equal length headers, and different diameter piping. There is no header/exhaust perfect for every setup if you are trying to make power. Each one will respond different to your mods at specific RPMs.

read some of tony's (motordyne) posts. he does a good job of explaining it.

 

my head hurts.

 

One thing to note is that the OP said he bought that exhaust banged up and fixed it. Who's to say that cross pipe didn't move due to the damage? But either way, even if it was perfectly centered, it would still intrude into both sides, yikes indeed! If you want power, spend that exhaust money on a spacer, high flow cats/test pipes and a tune :-)

 

true... if purely looking for power for the lowest price, I would do art pipes, spacer k&n panel filter and tune.

 

Defender you obviously no Zero about mechanics or how exhaust systems should be designed! That pipe on the crossover in the pic is restricting exhaust flow no less than 40% which is totally unacceptable in anyone's world. I just sent a pic of this to HKS USA and hope I get some type of response and I'll be adding a Magnaflow crossover which appears to cost somewhere in the neighborhood of $200 parts/labor. I have always been a HKS fan and supporter since my last two cars ran their exhaust systems.
Gary

 

Just received my first response back from HKS, they posted some bull **** about their warranty's and how we'd need a sales receipt from where we purchased the exhaust system. I responded with a question about their HKS HP exhaust systems referring to the pic and was this the type of crossovers all our systems have that were designed for our G35s? Waiting for an answer, if I ever get one....
Gary

 

Gary, I would go ahead and just purchase the x-pipe anyways. Less than $80 shipped. It's cheap upgrade now with this discovery. Who knows, your copy may not have this problem. The only issue is that you will be stuck with a quieter exhaust and lose the unique sound.

 

Second response from HKS, that is not how the crossovers were intended to be made and they've been doing so since 2005 for the G35 and 350Zs. If we have one made like this warranty should apply. You really don't know if the restriction exists unless you cut your system up. Really considering the Magnaflow X-Pipe or Crossover. From the dyno sheets I've seen previously the crossover flows better which is exactly what I need....
Gary

 

I don't think so Jairen, you're just replacing one crossover that may be restricted with another you know isn't. The system should sound close to same, although after installing my HFCs this past weekend a little quieter couldn't hurt....
Gary

 

A borescope may reach far enough in to see what the pipe looks like without cutting anything and there are digital ones now that you can use to take a picture. If I get totally bored at work I may try....

 

What I find humorous its the fact that there isn't a single shred of proof that one of these dual exhaust's makes any more power than a well designed y-pipe to single exhausts. The only major deference is the sound and the weight. Hks churns these exhausts out at a pretty good rate. And yes your paying for the name. I think it truly is just a quality control issue....besides if you bought it new you paid too damn much