Hello From Florida

:welcome: to Club-tC. You aren't going to see all that much in gains by upgrading the CPU, unless your F/I (Forced Induction). If you do decide to upgrade to a supercharger or turbo, getting an emanage or piggy back might do you some justice. Being that your N/A (Naturally Aspirated), don't waste the money. As far as headers go, they are worth the investment, I have set I am going to be putting on very soon. If you do get a header go w/ a 4-2-1, or 4-1. A 4-2-1 will perform better at low/mid power range and a 4-1 is for mid/high power range. I would also spend the money and send the header to JETHOT The Hottest Header Coatings! Jet-Hot, jet coat, hot jet, headers, coatings, sterling, Header coating, Ceramic coating, corrosion protection, friction reduction, thermal barrier, Metallic Ceramic Coatings, MCCI, metallic ceramic, exhaust coatin, I had mine done by them and I must say their work is top notch and fully warrantied. With a header you'll gain at minium 15HP, I would also upgrade your OEM crank pulley w/ a lite weight one from Agency or NST (Non Stop Tuning), just do not buy under driven pullies.

Have you upgraded your rear sway bar, struts or brake rotors?

If you have any questions, the name is Scott and own a 2006 Scion tC that has around $10,000 in mods. I would be more than happy to answer any questions you may have.

Your more than welcome, I do what I can with the knowledge I have. The lite weight pullies will reduce some weight and strain on the motor and allow for your RPM's to climb faster. You may also pick up a couple more ponies. They are well worth the money and won't hurt you, they'll help you. Now as far and the I/H/E goes, the better the engine breathes, the better it performs and can increase MPG. Also keep in mind that exhaust manifolds aren't as smooth flowing as a header and can restrict HP/Torque. This also applies w/ using a full synthetic oil ex. (Royal Purple, Mobil 1 5w20/5w30), which helps the engine perform at its bests w/o sacrificing gas mileage, better lubracation, longer engine life and not having to change your oil every 3000miles.

Wow Cadence, good job on being super active in forums and helping out members.

Austin, yes that's the general basic aspect to think of. However if you weight the pros and cons of the price/performance of the intake manifolds they make for us; you will understand that very few Scion enthusiasts have an aftermarket intake manifold. I believe most of intake manifolds available for us are more tailored to boost applications, at least from the distributors that we've worked with.

From what reading and research I have done, I wouldn't waste the money on either a Decendant or Weapon-R Intake Manifold. Our OEM Intake performs very well as it is. I have yet to be convinced that any aftermarket intake manifold is going to benefit our cars. Show me some dyno sheets/charts, then I might lend an ear. I do have to agree w/ Mengsta, having a boosted application would make more sense to see any possible increases in HP/Torque. The VVT-i is a learning curve motor, it adjusts as we drive. This also will apply on performance chips, not worth the money and I'd be hard pressed to see any substantial gains. Most people I have talked to have said that chips tend to throw CEL's, the engine runs lean/rich and losses in HP/Torque. As I said prior, show me a legit dyno sheet/chart w/ a before and after, then I'll run right out and buy one.