I want to get my car tuned and I only have a pulley and CAI. Its suggested to wait until I get an exhaust to do the tune and I can understand why but how much of a difference would there be in gains from a tune with a performance exhaust and a tune without an exhaust? I am not talking about the gains including the exhaust but the difference of what % power gain a tune will net with / without an exhaust.

I would like to get an exhaust but while this car is my daily driver and goes on the highway I don't really want to go away from stock and chance any extra drone than the stock has at highway speeds. After school when its a track only car is a different story.

Thanks,
k

 

I have a Volt and there isnt much drone to it at all IMO. Also when getting a tune recomend getting bigger injectors.
Jack

 

I recommend doing the one-ball upgrade (just did mine today and am loving it) as a good budget minded compromise between a full aftermarket exhaust and stock. I've found there's a little more noise with the windows down, a bit of a drone at some part throttle times, a more pronounced pop when lifting off the accelerator from higher RPMS and a slightly deeper tone when idling. All of the increased sound is negligible when the radio is on.
For the most part the tune with and without exhaust won't make much of a difference but the increased breathing at the top end, where the stock car begins to really struggle, will be maximized much more with a tune and an exhaust.

 

why get the bigger injectors?

 

Depending on the tune, they may or may not recommend 380s for basic mods.
For instance, the GIAC flash recommends 380s if you get the flash for the 17% or 19% pulley.

 

jan said that if i go with 17 or 19% pulley, i will need injectors. he did not mention getting injectors for a 15% pulley. anyone know how much more hp/tq will i get going from 15% to 17% pulley?

 

i was actually talking to my friend about this just last night, about the need for bigger injectors. he goes "why bother? the tuner's gonna lean out your A/F ratio anyway" we were also talking about the possibility of having an Apex-i NEO in my Mini for the tuning. i'm from the philippines and there are no ECU flashes here, hence my considering the option to get an S-AFC

btw, my only mods at the moment are M7 16%, DDM CAI and a custom (aka a lot cheaper) exhaust

 

For RMW tune- (confirm with Jan on the details below)

Your CAI and 15% is OK with stock injectors (although the 380cc JCW injectors come with JCW Supercharger). Add the one ball exhaust if you want, it's cheap and you loose weight without much negative for loudness. I think you can do the retune then add any cat back exhaust in the future with good results.

For quiet MCS exhausts- JCW or Borla Street.

15% pulley and stock injectors is fine for retune as is. Probably 380 cc injectors will work as well.

17% and 19% need to add 380 cc (JCW) injectors if using stock cylinder head.

17-19% pulley with ported and polished (Jesus) head and cam, then 440 cc injectors required to work with RMW tune.

 

Addding injectors gives more fuel to add or play with while tuning, im running a 17% reduction and running very lean up top, about to get some bigger injectors and get jan to tune it. I would definately do it righ tth efirst time and get injectors.

Jack