blizzard520

I do use 91 right now so hopefully we will see the improvements from the tune.

Nuke

Using 91 octane on the stock 87 tune is a waste of money; no gain. A good custom tune & CAI on the 4.0 will net you about 15-20 RWHP over stock.

tradosaurus

Paint flames on the side of your car and add a huge spoiler. That is always good for +20 hp.

Dino Dino Bambino

Yeah just like the leaf blower electric supercharger, turbonator, fuel magnetizer, vortex generators, Type R stickers, NOS stickers, and coffee can exhaust.

So_Cali

When I had my 06, I went CAI and Tune. Definitely woke the car up and made it more fun to drive. That along with gears and maybe an aluminum driveshaft are pretty much the only mods you can get to squeeze/ free-up the most horses. Only other option would be going F/I