OKC370Z

I purchased the Stillen FI kit and had Chris with Failsafe install it. I did have to wait on the new tune because this all took place right as Chris ordered my FI kit. So from day one my '09 with 7 AT has had the "new" tune. I feel a lot like Phimosis, where I'm a bit disappointed that the car did not put down the advertised power and torque. I'm more specifically disappointed in the amount of torque gained. My numbers where 389 whp / 290 Wtq on a fairly mild day, ambient was in the mid 80's. I find it interesting because Chris custom tuned LateralG'z car and the dyno results were very close to mine, except that ambient on the day Chris tuned LateralG's car was in the 100's. Also, note that LateraG'z car has a standard trans.

I owned a 2001 Mustang Bullitt GT that had head work, cams and custom tune and was seeing 12 psi of boost. That car with a conservative custom tune put 450 whp to the ground on a mustang dyno, but (and a big but at that) the drivability of the car was never right and no matter what three different tuners tried, the idle or steady state throttle was never right. One thing I can say for the Stillen tune is that drivability with the "new" tune is superb and anyone who drove the car not knowing there was an FI kit under the hood would know any different.

I also had Chris install Stillen's catback system and I really like how smooth and progressive the power and sound is with the FI, catback combo. The rough sound of the stock engine is gone, replaced with a really nice exotic exhaust note that is not intrusive in anyway and most importantly absolutely no drone at any speed in any gear. The SC puts out a very small whine at idle but disappears when you accelerate, replaced by the intoxicating sound of the exhaust. Most might not find the exhaust sound intoxicating but I come from a history of V8 motors and I love the sound of a strong running V8. I have not had much experience with V6 motors and I was concerned when I first seen how big the exhaust tips are on the Stillen exhaust. At first I was afraid the car was going to sound like a Honda Accord with one of those coffee cans installed on the back. I'm very happy to say that it does not even come close to sounding like that at all. I am quite pleased with the sound from idle all the way to redline.

As for performance as I stated I am a bit disappointed but not to the point where I'm thinking about removing the system and demanding my money back. After all the kit is priced very reasonably for what all comes with it (at least at the intro price). The power is smooth and the tune does increase the performance right off of idle as well, the car has a lot more thrust below 3k rpm then stock and throttle response is great. With the 7AT first gear is almost useless, if you step into it hard in first the tires will just go up in smoke. I find myself short shifting about 4-5 grand into second and then get into it and it still breaks the tires loose and will kick out sideways very easily if desired (which I desire allot).

What I don't understand following all of the FI threads, is that all the operating systems, whether GTM or Stillen, are operating at 6-8 psi of boost. Yet the numbers produced are all over the place with minimal differences between cars as far as exhaust systems go. And this is with some of them having Stillen's tune and others with custom tunes. IMHO, if the same motors are operating at 8 psi of boost (which is just a reference of manifold pressure based on a certain amount of air moving through it) then they should produce very similar amounts of HP. The only differences would be based on the SC itself and its curve. Most centrifugals these days use the same technology and design concepts to produce their SC's. If one SC is making considerably more HP than another it would have to produce significantly more boost overall or in a specific rpm range. Take for instance GTM's SC which makes more HP than Stillen's. It supposedly is doing so at the same boost levels, and if it is making more boost earlier on in the rpm range of the motor it would certainly make more than 8 psi of boost at the top end of the rpm range. Therefore, it just does not equate that the GTM kit can make that much more than the Stillen which is producing the same boost levels at said air volume through the manifold. Because of this it is my opinion that the GTM and Stillen kits make relatively similar gains on a stock 3.7 no matter the exhaust setup and the differences we are seeing in dyno graphs is due to types of dyno's used, ambient conditions (temps, humidity, elevations, etc.), initial dyno software input, car setup on the dyno (is it strapped down tight, could it be too tight an impose to much resistance), etc. There's a lot of variables involved and like many of said before a dyno is tool good for tuning and comparing baseline with added mods on the same car on the same dyno.

I have chased horsepower and numbers before with the Mustang Bullitt and when doing so I used three different tuners, all with different dyno's and they all indicated very different results. I also discovered as we decreased pulley sizes on the SC to increase boost we would only gain 15-20 whp per smaller size. I found this to be true as I watched others do the same with different SC's on the same or similar motor as mine.

In conclusion if you look at everyone’s results that have posted so far, there is significant variances in HP and TQ from one car to the next even with the same FI kit. This tells me that variables mentioned above play a significant role in what the dyno graph is going to look like and IMHO I don't think there really is that much difference. For instance take a look at my numbers compared to LateralG'z, they are very similar despite the fact that mine has the Stillen tune and G'z has the custom tune. Both were run on the same dyno and the results due differ slightly but ambient conditions were different at the time each car was run.

You really want to know if the GTM kit is producing that much more power than the Stillen? Take two Z's with the same setup (exhaust, tires, etc.) and ensure both FI kits are producing the same boost levels and then have one driver take them both down the quarter mile back to back. I'm willing to bet the difference is negligible.

Oh, and I forgot to say that Chris at Failsafe Performance in Tulsa did an outstanding job of installing everything on my car and when I went to pick it up it was detailed and waiting for me. I highly recommend him and his services.