I have heard (from several sources) that an H-pipe in the right place will help performance. However, if that H-pipe is in the wrong place, performance can be worse than no crossover at all.

Does anyone know if the same is true of an X-pipe?

I just read an article in my Chevy mag on a test with open headers compared to an h-pipe and x-pipe. The dyno figures for the x-pipe were almost identical with those of the open headers. The h-pipe setup on the other hand lagged a good amount behind in power figures.

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'91 RS, 375hp 350
New paint-solid black
ROH Snyper wheels-17x9 wrapped in 275/40/17
ASCD SS hood, High-rise Z-28 spoiler,shaved handles/antenna,
Hooker super comp 1 3/4" headers,dual 3" exhaust,two 1-chamber Flomasters,machined hi-perf GM heads,Holley double pumper 650 w/50cc pumps,Power Plus 360* high rise aluminum intake,Edelbrock Elite valve covers/14x4" open air cleaner,Mallory AFPR,Proform HI-perf HEI disributer with curve kit,Crane 292 cam,Eibach Sportline springs,KYB struts/shocks,completely rebuilt steering linkage,36/24mm sway bars,12.7 steering box,wonderbar,145 gauge cluster,Auto meter gauges,dual guage A-pillar pods,180* thermostat,dual push/pull cooling fans.
75-125 shot NOS system planned.

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