I've got the MSDS headers(Vortech spec) and y-pipe. I had stock exhaust manifolds and SHO-Shop y-pipe before this set-up. The SHO-Shop y was the original design with built in hi-flow cat. New set-up uses the stock cat. Vehicle is 98evo 0,SVT. Other mods: KKM intake, Pro-Flow 75mm Maf, Borla cat-back. Stock chip.
Dyno results:
Stock- no data
Above mods with sho-shop y (no headers)
max hp 174.0 max tq 154.4
Switch to MSDS headers and y-pipe, stock cat
max hp 179.3 max tq 156.7
As you can see, this is no where near 14% gain! More like 3% @ the wheels over the Sho-Shop y-pipe/cat. May be able to get more with different cat, and a chip burned for these mods will definately help. You might show a much larger gain compared to a stock SVT dyno reading, which is probably where MSDS got their 14% number.
Note: Both runs on same dyno and air temp was maybe 20deg cooler on the header run vs. the first run.
Throttle response is improved with the headers and I have noticed a gain in fuel mileage, but I am disappointed in the hp and tq gains.
