I was hitting 99% at few places too, usually up to 95%, but according my tuner I dont have to touch injectors, unless i will go corn fuel.

 

I guess it's not absolutely essential to get injectors but after doing quite a bit of research on duty cycle, pulse widths etc. it really isn't good to let your injectors work that hard. At 90%+ duty cycle, the injectors don't really have the proper amount of time to "rest" between cycles and you're going to get inconsistent amounts of fuel which will affect proper atomization and combustion, which will not give you consistent results when tuning. I felt that for a relatively low cost to upgrade, it's well worth the price to be running more consistently for the rest of the life of my car which still only has 43k miles.

I don't really understand why a tuner would say you don't need injectors when seeing duty cycle numbers that high.. BUT I'm not a tuner, just a self-educated researcher based upon stuff on the internet, so.... lol

 

98% with 550cc?

 

sorry, I meant when I had stock 380cc

 

Good lol.
I was hitting 107 with oem 330cc and am upgrading asap
08 vq35hr

 

Glad those ported manifolds are working well for ya. Also seems like you'll be making more power than when I had them. Definitely interested in your numbers when you get to hit the dyno.

 

Thanks man! But I just don't know about my power numbers now.

I feel like my exhaust is really holding me back now since it's 2.25" and the Q300 has those chambered mufflers too.. hmm.

 

Doubtful.

 

I switched from a Top Speed exhaust (2.375") with Motordyne y pipe to a full Motordyne exhaust and didn't notice anything different. I had the car dynoed on a different dyno but the numbers matched up.

However, since I've switched to single exit, i noticed more pick up in mid range, i haven't dynoed this setup yet.

 

I'm just basing it off the charts you can find online about how much HP a 2.25" exhaust can support before becoming a point of restriction. For mild NA G's it shouldn't be a problem, but in my case I would say it's a restriction.

https://m.roadkillcustoms.com/determ...t-tubing-size/

 

3.7 liters is 225 ci, and according to that chart recommended tubing size for a dual exhaust is 2.0 to 2.5". Even if you had a larger engine with 350 BHP, the chart still says 2.5" dual pipes is recommended.



Agreed. But the OP really wants to upgrade. And it reads like he's going to convince himself it's necessary, whether it is or isn't.