My G is getting decently high in mileage now (~168,000), and it obviously doesn't have the same power it used to. It still feel like it runs really great for being as high as it is, and I haven't experienced any of the ticks or other problems some high mileage users complain about. I push it hard decently often still and its still pretty fast. I've done a handful of modifications which all seemed to have either affected the mid range or higher, but I'm unaware of how they affected me negatively perhaps. Everything I've done is removable however, so if removing one component helps me out, then great. I'm trying to figure out how to get a little of my torque back and get quicker starts. I remember when I used to get slightly kicked back on off the line starts and have an pretty good 0-60, but now it seems sluggish until I hit roughly around the 2,000-3,000 rpm range, and my 0-60 is less than average for a G. Is this just the usual results to expect from an aging engine? Or is one of my mods, or a faulty exhaust, or other component perhaps the cause? Any advice helps.

Its a 2005 G35x. My current mods are:
-5/16 plenum spacer
-Z-tube w/ JWT pop charger
-throttle body spacer
-kinetix HFC's(very recent, and improvement was definitely noticed.)
- my muffler is a generic one installed by the last owner, I beleive it says "hyperflow" on the bottom or something similar.
- AMS lightweight pulley set
-SxExCx grounding kit

 

Have you tuned your car??? If not, you should think of Uprev... A pro tuner can get your air/fuel ratio optimized.... You could be running lean... Also with the high miles, spark plugs may need changing if the prior owner hadn't changed them..... Think about the camshaft and crankshaft sensors needing to be replaced also.....

 

I did spark plugs, but not the crankshaft sensors or camshaft, thanks. Tuning is certainly on my list, I'm just unsure of which way I should go seeing as there aren't any close to where I live.

 

You can get a custom e-tune from Uprev for the Osiris. They send you a basic tune to the mods you have, you send back some info, and they keep sending you a tune until your car is tuned in.

 

If its been more than 10K miles since you did them swap in a new set of NGK Iridiums and get an uprev tune. You'll get all that power back and more

 

I would leave these alone unless they're failing/ causing a CEL

 

Any oil in the plenum? If the ECU is pulling timing due to knock you will feel the drop in power. I'd recommend changing out the PCV valve, putting in a nice catch can set up, and cleaning out your intake manifold, and cleaning your MAF sensor with MAF spray.

 

Clean your maf,

 

Thanks, I'll try cleaning the MAF sensor then.