I hate to try to get on you, but you need to seriously read a good book on forced induction if you don't know why the compression is different. Try to pick up a copy of Corky Bell's book on Turbocharging and it will help you understand a lot. Compression is an extemely basic concept. You have 2 major factors to deal with: cylinder pressure and detonation. The lower the compression, the greater the resistance to detonation. Also, the lower the compression, the less the cylinder pressure. Try running even 12 psi on pump gas on an 11.5:1 motor and kiss those new pistons goodbye. With forced induction, the amount of air volume is determined by the supercharger or turbocharger. The air charged in FI is already compressed before it ever enters a combustion chamber. You are compression it further inside the cylinder. In an NA engine it is solely determined by the ability of the engine to draw in the air. They are 2 entirely different principles. On an NA engine, every point of copression is good for 10% more power. On an FI motor since the turbo or SC flows the same amount of air into the cylinder, regardless of the compression ratio; there is a much lower difference in power between compression ratios. The only downside to the lower compression is what happens when you are not in boost. At lower rpms, particularly with a turbo when it is not spooled, the engine is running as essentually a low compression NA motor. It makes the engine spool a turbo slower because of the lower air volume.

If you are looking at pistons, they are going to run $600-700 a set. Keep in mind that the engine has to be removed, completely rebuilt and reinstalled. Figure on about $3000 for the rebuild from a good builder. It is only realistic in doing this if you are going a lot more serious than basic bolt-ons on an NA. High compression pistons aren't needed without getting a set of cams, springs and headwork for an NA(figure another $2000). This type of motor could easily push over 300 hp at the wheels(350+ flywheel).

The pistons though are not the biggest weakness in the VQ35DE engine. The most common failures are the connecting rod bolts(far too small) and the connecting rods(too thin to support over 450hp). If you are going to open the motor, a set of rods are a necessity before getting the pistons Figure $1000 for a good set of Crower or Pauter rods. If you are looking at going boosted, there is no point in going into the motor if you are just going to by an off the shelf SC kit. The power levels from those kits are designed for stock internals. Even a couple of pulley size changes isn't enough to justify going inside. Start looking at things like the Greddy TT kit than can support over 650 hp on a low compression motor with the right amount of fuel as a justification. There really isn't much of a purpose in building a motor to support 800 hp if it going to never see 400 hp.

04' G35 Coupe(finally in the garage)
6-sp Diamond Graphite/Willow w/Premium

 

For the power range you want to run, you will be fine with stock internals. People are blowing their motors with the superchargers becasue the fuel isn't tuned right. I've seen several dynoes with A/F ratios in the 13-14.5:1 range under boost. Detonation is very possible if it isn't richer. The part where you have to cautious is in the tuning the fuel. IF you have it installed and tuned right, you will never have to worry about the internals. I ran a Vortech V1 supercharger on my Maxima for 3 years on the stock 10.0:1 compression ratio. I was running 6.5 psi(stock pulley) to 9.5 psi(3 sizes smaller pulley) without having any problems and needing race gas. My A/F was 12.1-12.3 across the entire powerband.

The variable pump on the ATI seems to put the A/F all over the map and I have yet to see one that is tuned right in all rpm bands. While I like ATI, this is making me think twice about their kit. It isn't an issue with their supercharger, it is the fuel tuning. If I were to go ATI, I would get it without the fuel pump and go Greddy E-manage instead. Now some people are getting the Vortechs on their car. An auto sedan put out almost 360 rwhp with only an exhaust in addition with a perfectly flat and linear fuel curve at 12.0:1. Fuel tuning is a lot easier with the Vortech. With that tuning, he will never have a problem as long as he runs premium gas.

04' G35 Coupe(finally in the garage)
6-sp Diamond Graphite/Willow w/Premium