Say What again!
Join Date: Sep 2009
Location: Washington Township, Michigan
Given they use the same part number, I believe you would have to the speedometer recalibrated in the tune to account for the taller final drive ratio. But yes, it would improve highway fuel economy at the expense of some low-end acceleration. Given the HHR really still isn't that heavy, I'd say it won't be a major deal. And since you have to pay someone to tune the computer (though, being a 2006 makes this much, much harder to do), you might as well pay for them to tune it as well.
But like I said, tuning an '05-06 Cobalt/HHR is much harder than '07+.
1986 Chevrolet Camaro IROC-Z - Wrecked/Sold
1998 Chevrolet Cavalier - Wrecked/Donated
2007 Chevrolet Cobalt LT - M62 Supercharger, Ported Throttle Body, 42 lb/hr Injectors, Intense 2.9" Pulley, Cobra Heat Exchanger, SS/TC Exhaust, TTR Engine and Trans Mounts, Trifecta Tune, ZZP Header and Downpipe, '08+ FE5 Struts/Shocks, SSC Springs, FE5 Control Arms, SS/SC Front Swaybar, Powell Hardcore Rear Swaybar, 18" MSR 045s, Dunlop ZIIs, Nightshaded Tails/Side Markers, Shorty Antenna, Black Bowties, Black Grilles, Black Headlights, Dual JL 12" w1v2 Subs, A/D/S Front/Rear Speakers, Pioneer 7" Touchscreen, G85 Recaros, Leather Rear Seats, 160 MPH Cluster.
2014 Chevrolet Cruze Diesel - 17" MSR 013s, Black Bowties, Black Tails, UR Rear Lower Bar
1981 Chevrolet Camaro Z28 - JVC Ribbon Tweeters, SEAS Mids, Pyle Woofers, Kenwood Tape Deck, Zapco Amp/Equilizer, Ceramic-Coated Longtubes, 2.5" Pypes Stainless Exhaust, Bilstein B6 Shocks, GW U/L Control Arms, Hotchkis Springs Sway Bars, DD HDX Cluster
2017 Chevrolet Volt LT - Black Bowties