Originally Posted by TBatt

I've been running the Stillen/TopZ system for several years now and about 8K miles problem free. Here is what I have observed:

My SC is setup with the 9psi pulley on the SC. At ~3000 rpm he SC is just starting to output more air than the engine is taking in. I can tell because the boost gauge is showing zero pressure and the blow off valve is starting to open and hiss. This equates to about 80mph steady cruise. So, if you have a MT6 you will need to down shift to third if you want maximum boost or fourth gear if you want to be easy on the tranny syncros. When the engine hits red line (7500) it will be making max boost and power. The engine will drop rpm by about 1500rpm when you grab the next higher gear. Now you are down from max power but at the power levels we are at you get to the next gear pretty fast.

Turbos cars need load in order to produce boost. So at the 3000 rpm range the turbos will spool up and provide lots of torque without down shifting. This could be very damaging to your engine as we all know these engines do not hold up well when producing a lot of torque. A down shift with the turbo car is needed as well to get the most power and in this case ease the load on the engine. Now here is where a big difference occurs between SC and turbo cars. During a shift, the SC and boost is exactly where the rpm is. No lag, it is directly driven by the engine. Turbos, on the other hand, will actually spool down during a shift and have to accelerate back up. That is why most guys use a automatic tranny for drag racing. Depending on the turbo setup, this can cause some on and off power delivery.

Cars that have sophisticated turbo systems (Porsche, GTR) get around some of this with careful design and darn good engineering. They can feel like a big ol' V8 on the low end and they have control to not over torque if you don't downshift.

Anyways, enough of my two cents worth. I love SC and if you drive "normal" the car drives perfectly normal and if you put your foot in it it responds like a stock car until the rpms get up. No sudden surprises with unexpected boost. Safe.