Hello friends, I have an 04 g35 coupe, only modifications so far are a Spectre air intake and a TopSpeed catback exhaust system. Soon however I am planning on ordering Motordyne's 5/16 plenum spacer (and was thinking about but not sure yet NWP's 75mm throttle body), and then Berk High flow cats. Also was thinking about an aftermarket Y pipe just so everything was done all the way from the cats to the tips but still iffy on that as well.
Then once I add those mods in I'm planning on driving two hours to Charlotte(closest place to me that tunes VQs) to get her tuned. So I guess my questions are:
1. Do any of you have experience with the plenum spacer or throttle body or combination of the two? And what are your opinions? Any hood fitment issues with the combo? Said something about that on NWP website.
2. is an aftermarket Y pipe really going to change much if I put one on at the same time I put the high flow cats on?
3. I know just the plenum spacer alone isn't enough to make a car run lean but Is it smart to drive my car for 2 hours after installing the plenum spacer/throttle body combo without a tune? Or would it probably run lean and damage something?
4. Also any recommendations on additional mods I should throw on before my first tune?
Thanks

 

The car has to be running VERY lean to actually cause damage, the computer is constantly changing the fuel trims to compensate, once it hits a certain threshold the service engine light comes on and it STILL has leeway to adjust the fuel mix. If you have any concerns then plug in an OBD2 scanner and read the O2 and fuel trims to see how much extra air it had to adjust for.

My fuel trims sit around +8% stock, no mods. I think +20% is when the service engine light turns on, unsure though.

 

Thanks man. Anyone else have any experience/knowledge about the aftermarket y pipe? I don't imagine it would make a big difference besides shedding a few pounds just wanting to be sure

 

See above in red. Also on the intake either go back to the stock airbox (revup) if you can find one with a z tube and drop in a quality filter like the AEM or K&N. Or pick up a Stillen or R2C intake. I am a huge fan of the R2C as it has one of, if not the best, filters on the market and it seals against the hood to help prevent heat soak. Your Spectre just sucks hot air from the engine bay which is a bad thing. Other than that you will have done all of the basic breather mods and you'll be ready for a tune.

 

Thanks man.

 

You might also consider the etune route; you can get a decent tune without having to drive 2 hrs and save some money.

 

Yeah but then I have to buy the whole uprev kit for $550 and then buy the etune for $400, or I can just buy the license for $300 and drive 2 hours to pay for the tune. Will actually save a little bit probably

 

I just sent you a PM. The price of tuning is included in the $550, there are no additional fees. I would check with the shop you're planning on going to, they often have a package price that you have to pay for an Uprev dyno tune, with the license included you won't get out the door for less an $600, average price is about $750. JUST for the license and tune, no reflash cable.

 

Kgoudie, welcome to Driver! You should have spent more time here before you wasted your $$ on your current mods! If you're considering the purchase of an aftermarket y-pipe you don't have a "Cat Back Exhaust!" Spectre intake will kill more hp than all you'll ever get with any modifications once your weather reaches 80 degrees! Stillen CAI is the only intake that won't kill hp during warm weather, it's made of plastic composite! Plenum spacers and TB's won't cause you any hood fitment issues! Berks HFCs cost me $300+ because they failed within a year, the manufacture refused to back their warranty! I've been running Fast Intentions for a long time without issues. You won't have a lean condition running a plenum spacer and your current y-back exhaust!
You need to spend a few hours reading all the stickys at the top of the coupe page, then use our Search! Doing so would have saved you big $$! "Your Welcome!"
Gary

 

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