I challenge you to flow test the APS 3" and the SVRtech 3" and let us know which flows better. IT is my humble opinion that the X-pipe restricts flow rather than helps. I, being a pathetic farmer, don't have the capability to flow test these two exhausts, so I can not say definitively, but my money is on APS. FYI, the SVRtech tapers to 2.5" at the point it connects to the dump pipes - yes, it connects directly to the dump pipes off the turbos. This means no 3.5" test pipes for you. Instead, you get to run the relatively restrictive (in relation to the big test pipes APS offers) cast dumps into the 2.5" openings on the SVRtech exhaust. I am no physics major, but 3.5" piping into 3" exhaust sounds like it would flow better than 2.5" into 3", but again, I am a just a simple minded farmer.

If you are buying APS products, most come through GRD, so that is where I would recommend you buy your products

 

IF I got the SVR exhaust from scott I would have it mate to the APS 3.5 Test pipes so it would be a 3" back. X pipes have been proven in many applications to produce a nice bump in HP and mainly Torque, It was dynoed and showed a good increase in TQ on a JWT TT kit and made nice gains on Scotts Greddy TT car as well. and I rather have TQ than a rediculous amount of HP.

Anyways I dont like the small tips on the SVR, I need an exhaust with large Ti tips.

Im getting closer and closer to going custom

 

Why custom? ImHO, custom = hack job. There are nice exhaus setups out there. with a custom setup, I would really question the flow of the exhaust. You run the APS TT setup, why do you seem so reluctant to buy the exhaust they designed to run with it?

 

The APS exhaust is nice, but i really wanted something with nice 4" or larger Ti tips and an X pipe for the TQ.

I wish i had to funds to buy both systems and test them!

 

here is a pict:


i need to make a correction tho- it's not 50mm. its more like 57mm ...

 

BTW there are some nice shops here in SoCal that can make a really nice mandrel bent exhaust system, there really isnt that much to a true dual 3" exhaust atleast in my opion, I mean how diffrent are these exhaust from each other? they are all the same besides location of H pipe, if any, and the Canisters. Reason i have gone with a custom set up yet is because of the tips, I need them to be straight not angled.

 

So the Overall diamter changed from 2.75in to 2.25 in for about 1.5 inches, will the really make a diffrecne in flow.

APS 3.5in down pipe - 2.25in then 2.75in all the way back

Why is this so difficult

 

those changes in diameter could potentialy cause turbulence

 

the X pipe does not impeed flow. it HELPS it. not that i needed conformation myself, but plumpz had his installed by an engineer at penske, that fully understands what the X pipe does and commented it speeds exhaust flow by 2-3 times. it acts like a carb venturi to actually speed up exhaust flow in both front pipes. again, you only have one cylinder firing and discharging at a time, so only the spent gases from one cylinder can ever pass through the X pipe at one time. it is 3" through the center not 2.5". after the X pipe you also nearly double the effiecientcy of your muffler and resonator effectiveness, this is the reason my exhaust is the quitest 3" dual you will find. yes, i have heard other 3" systems next to mine and know this.
the X pipe will also help ride over small imperfections in the exhaust design. meaning you will only match the hp and torque IF YOUR EXHAUST IS PERFECTLY DESIGNED FOR THE BREATHING CAPABILITIES OF THE MOTOR. the X pipe makes this system effiecient on guys running 7psi all the way up to 20+psi. it would take hours of testing to perfectly tune an exhaust to run at its peak on each and every single motor combo.
time and time again we have seen gains in both hp AND torque. even moving from smaller exhausts when torque should have dropped. it not only had a higher peak, but extended out further in the rpm range. i have installed the system on cars that right after leaving called me to tell them they had clipped their maf signal on a precisely tuned motor. this means we are hitting greater airflow at the lower rpms, and pulling larger overall torque numbers too. yes the hp still gained like a typical 3" system would.
most of my car experience is from the domestic market. it has given me a slight advantage to bring what i know from a motor with 50+ years of racing history, to a motor with just a few years of history. the X pipe is one of those things. i may not be the best tuner in the world (i would if i had a dyno though, lol) but i have alot of knowledge in shear mechanics and engine theories.
btw- i hope i don't need to mention this again, but, the VQ35 is a more effiecient motor to make use of an X pipe than a V-8 where the idea was born and used extensively.
this post is not designed to sell my exhausts as they are so expensive for me to produce, you will need to seriously talk me into making more, but just a refresher to the multiple benefits an X pipe gives.
H pipes will give a slight advantage, but the air in the crossover will need to be effected before it can effect the pressure in the opposite pipe. an H pipe will mostly help with rasp with modest flattening of torque and hp peaks. a true X pipe will gain larger benfits.

 

hey george, ya i tried looking for some Ti awhile ago for ya, but dang, they want $1200 for a 4"dia 10' long piece. that is a minimun order. not to mention welding Ti to stainless is not an easy or pretty process. that is why most all Ti tped exhausts have the tips fastened by rivets or other methods.

 

If the engine was just a tank releasing a fluid for example, thru the X pipe, it would be totally useless. However, the engine is not a tank, but instead works in cycles. No 2 cylinders are ever firing at the same time. Thats teh whole point behind the X pipe. The x pipe allows to create a vacuum at the exhaust valve caused by the pressure wave of the opening and closing of the exhaust valve. It works in ALL situations, including turbo, supercharged and N/A. This vacuum helps you to pull the air out, instead of having the negine force it out, increasing the efficiency of the motor by quite a bit.

 

The SVRtech does not have testpipes. It is one straight pipe on each side to the xpipe.

 

Take an APS TT setup like the OP is running. One with the 3.5" pipes into the 3" and other other with the cast dumps into the 3" SVRtech. See which one makes more power. I have 100 bucks on APS.

 

That tapers to 2.5" near the flange and does not allow APS owners to run the big 3.5" test pipes

 

It would be easy to cut the pipe down and reweld the flange wouldnt it?

 

not as easy at it sounds. The bends may not allow fitment to a catback type bolt-up.

 

Hmm that would suck, Going to have to do some more research!

 

hey george, the first exhaust on my own car cost me close to $3000, lol. you might be able to find someone to do it cheaper, but you will be really hard pressed to find someone with a good true mandrel bender that can do stainless for a one off system.

 

You know if your willing to make me a exhaust im going to get it from you scott I was just thinking incase you cant make one any more, i just really need some 4-5" tip even if they are stainless i can get some Ti sleeves to put on them later on with rivets or something. Let me know if you can make me an exhaust scott, Ill be getting it in the next month or so.

Thanks

 

want to head up here? then we could do some trick stuff! the trick is finding the Ti. i did internet searches across the u.s.a and could not find even small remnants to use. i even entertained the idea of even trying to find flat rems and bending them to circles, then welding up the seam, not sure how it would look though.
i do agree that the aps 3.5" test pipes are a nice piece. for those who don't know the theory they are trying to reach with it, it is nothing more than an expanded section to try and turn circular exhaust flow into linear again. that is the only gain from the expanded section. you will find that in any turbo/exhaust book.

btw george- we can get short chunks of 4-5" stainless for tips, but it would be so much easier if your car was here, or i would have to make all new jigs, yata yata, in order to feel comfortable sending it to ya. if you got the aps test pipes, we could pretty easily adapt both systems together, then you would have the best of all worlds.