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NGK Iridium Spark Plug One Step Colder 2309



19 Reviews
4.9 out of 5 Stars
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NGK Iridium Spark Plug One Step Colder 2309 ( Part Number: LFR7AIX)
Works as expected 4 years ago
Great product and as always RSD service.
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 5 years ago
Car idles great and is smooth throughout the RPM range. The only downside was the install, but that is Subaru packaging for you.
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One of those must do mods for stage 2+ 5 years ago
I did so many other mods at once I can't say I noticed a difference. The rumors are true, the install sucks but it's definitely doable. Just takes patience, and a second set of hands definitely.
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Great spark plug! 5 years ago
These plugs are the best. I love that they come pre-gapped. They helped to fix a rough idle/misfire issue on my '11 wrx.
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Smoooooth 6 years ago
Installed these as soon as they came in the mail. I previously had Denso's installed and so far the NGK's seem to idle smoother. As always, fast shipping and great service from RSD. Thanks again guys.
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Great! 6 years ago
Easy to install, fit like OEM, car runs very smooth and always A+++ service from RSD!
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Better fuel economy 6 years ago
Installed these plugs as I was jumping from a Cobb stage 2 map to a stage 3 map. My car ran better on both stage 2&3 maps as well as my MPGs going up. My car idles better and oddly I can drive in lower RPMs like creeping in traffic without my car wanting to stall.
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1 of 1 people found the following review helpful
Great upgrade. Difference noticed immediately.  6 years ago
I picked these up to run Torqued Performance stage 3 OTS map. Once we installed them the car felt noticeably better in revs and starting. Idle was much improved and pre-gapped! This is one of my favorite upgrades i've done to the car. Thanks RSD!
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great bang for the buck 6 years ago
Rob Mac
Just installed these on my 07 STi and omg what a difference.
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1 of 1 people found the following review helpful
2011 wrx 7 years ago
What a smooth idle! Car cranks over so fast!
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1 of 1 people found the following review helpful
Good product 7 years ago
Swiss Greg
Fit like oem. Good product
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awsome spark plugs!!!! 7 years ago
my 2011 wrx runs smother and its surprising how much more agresive a tuner can get with this plugs!
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Best plugs out there 7 years ago
Fit great and what a surprise for after tune:) would buy again and again and again....
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Nice NGK Spark Plugs 7 years ago
Nice and it fits well!
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Excellent 7 years ago
Chandler B.
Great plug and highly recommended for anyone running a stage 2+ STi. The price/power gain ratio can't be beat. You will be pleasantly surprised after switching to these plugs and getting a re-tune how much more aggressive your tuner can get with things like AFR and ignition timing.
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They fit, they work... 8 years ago
Factory issue plug with long life span. Nuff said...
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2 of 2 people found the following review helpful
 8 years ago
What a difference these made. It's like going from a beater to a bimmer in terms of how smooth my idle is now.
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1 of 1 people found the following review helpful
 10 years ago
I have always used NGK in my cars because of the quality of their products and these are no different One step colder is used because of recommendation from tuner.
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Upgraded 6 years ago
Once I started to upgrade the performance for my 2004 STi I realized that I needed the one step colder spark plugs and I knew that NGK was definitely the one I needed to get.
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NGK Iridium Spark Plug One Step Colder 2309 (Part Number: )