Grimmspeed PnP Exhaust Manifold w/ HiFlow Crosspipe Package 02+ WRX/STi. Our Subaru boxer engines kill our spool up time, most notably because of the very long pre-turbo exhaust tract(exhaust manifold, up pipe). To directly combat this loss of spool up we will port and polish all 9 inlets/outlets of your 3 piece exhaust manifold. We enlarge each port to match up with the stock subaru gaskets, porting 6-7mm of material at the entrance/outlet of each port and then tapering down into the port. This takes out the large steps in flow and smoothes out the port to port connections. Every piece is perfect matched to eachother for optimal flow.
As far as gains, 3rd party unrelated Subaru owners have seen ~15 whp/wtq gains, most notably in the low and mid range. You should also expect to see quicker spool up time.
The GrimmSpeed_ HiFlow Crosspipe is for you power hungry car enthusiasts that want to take it to the next level. The crosspipe is the pipe that connects the driver side exhaust manifold collector to the passenger side exhaust manifold collector. Subaru made the OEM crosspipe very small and restrictive with some very large steps in the exhaust flow path. The GrimmSpeed_ HiFlow Crosspipe solves all the problems of the OEM Crosspipe. With a 30% bigger bore and zero steps in the flow path, if you want optimal exhaust manifold flow, you need this pipe to achieve your goals. The pipe is constructed of 304 stainless steel flanges(most companies use polished mild steel to save on costs), thick 2in 304 stainless steel piping, and a 304 stainless steel flex joint.
You may need to tighten your turbo waste gate arm because of the higher flow. Start by tightening the wastegate one full turn and then test where you are at. Repeat if necessary.
We also offer an optional Ceramic Coating that help combat underhood temps, prolong the life of the manifold, and will also keep the exhaust gasses hotter which in turn speeds up velocity. Coated INSIDE and OUTSIDE if you choose to get it coated. The pictures of the manifold that is uncoated on the inside is just to show you what the PnP looks like.
We can also tap the exhaust manifold for your aftermarket EGT Gauge.