Do Hater pipes, Screamer pipes or Decat Pipes make power? The Ultimate 35PSI, 4" Exhaust Dyno Test!
Following on from our "Cat vs Decat" video (courtesy of XForce Performance Exhaust and GT Auto Garage), we are back to step the tests up to the next level!
Hater pipes, screamer pipes, catted or decatted? We put them all to the test on our big power Toyota Supra. This time though we will wind the boost up to a massive 35psi and see what differences these modifications make.
Once again, we hit up XForce Performance and GT Auto Garage along with Michael from MDSFab. to help us answer this one,
First off, we always wanted to run a 4in exhaust on the Supra, as we love the look of the HKS Super Drager muffler. Unfortunately these are just shy of 4in, so Michael hand crafted a beautiful new system using XForce parts to run the entire length of the car. But Michael was not done with just that - to get the most free flowing system possible, Michael crammed a huge 5" dump off the back of the turbo, along with a smooth 60mm wastegate that re-joined the exhaust 1/3 of the way under the car.
While he was at it, he made the system modular so we could select from any combination of:
Catted vs De-cat vs Screamer vs Recirculated wastegate vs straight "hater pipe" (hood exit exhaust).
Our JZA80 Supra makes around 850whp on 35psi of boost, so this was going to be quite a demanding task on the catalytic converter, as wefound out last time, even at 750whp, we were losing around 15hp at 25psi of boost.
We did 3 runs for each setup, with the results being quite consistent and within a few horsepower of each other.
It should be noted that the real difference only comes into play at the very peak power levels. Average punters with 500-600hp cars will see absolutely no gains in removing their cat, while people with 1000+ hp cars will probably see a further improvement by going a bigger exhaust all the way through.
For anyone interested in the T51 sound mod, hit up https://www.facebook.com/turbomodpro/
Stock 2JZ VVTi block
Kelford Cams V202-D 272/278 10.2mm lift cams
Kelford valve springs to suit
Hypertune 100mm intercooler & plenum
Turbosmart 60mm gate, BOV & RR-FPR
GCG Turbochargers Pty Ltd GTX3584RS-2
Turbomod.pro compressor housing modification (T51mod)
6boost exhaust manifold
Haltech Elite 2500 ECU
2200cc Bosch injectors
ARP head studs
XForce exhaust with 100 cell high flow cat
MDSFab 5" dump to full 4"system using XForce piping and bends
PWR Performance Products radiator
Southam Engineering R35GTR ignition coil conversion
Hardrace Suspension Australia engine and trans mounts
Wiring by Whitey's Wiring
Boomslang engine harness