Thats an LO manifold but from what i read, produces around the same gain as the HO.
1999 Pontiac Sunfire GT

Team Gates
a Dyno of the LO intake was done awhile back...... I believe the results of it showed 10 peak HP increase, and a loss of 1-2 peak lbs of Trq...... which is not to bad (since the LD9 starts with a 155lbs trq.)
I do not believe a Dyno has been done of the HO intake....... but being that it has a larger plenum, it should provide a slightly larger gain...... (compairing LO engines to HO engines, the LO produced 150hp, while the HO produced 180hp.... the only differences where cams, manifolds, and an increase of .5 in compression)
SPD RCR Z -
'02 Z24 420whp
SLO GOAT -
'04 GTO 305whp
W41 BOI -
'78 Buick Opel Isuzu W41 Swap
all i gotta say is that thing is super clean!!
how can you tell, visually, the differences between an HO and a LO manifold
i have the same manifold sitting in my closet... still debating installing it...
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ayo 8 Iz Enuff