Liazon,
Congrats & welcome to the MKIV Supra family!
Quick answers are:
1. Yes, roughly 30-50ish hp increase due to downpipe (aka DP). Increase is due to reduction in backpressure to the turbos by elimination of the two catalytic convertors. This results in the turbos being able to build more boost.
2. Exhaust - also known as a cat back exhaust. This is separate from (and after) the down pipe. Cat back refers to the exhaust system from the catalytic convertors on back. Performance increase is again due to reduction in turbo back pressure and corresponding ability to build more boost. Hp increases from DP and exhaust are separate and additive. In other words, you get both - to the extent that they both will allow an increase in boost.
3. Boost Cut Controller - this eliminates fuel cut off which would otherwise occur if boost exceeds stock levels. A FCD (fuel Cut Defensor) or BCC (and the BCC is recommended over the FCD), is needed to increase boost levels above stock. On a Supra TT, this can be done by simply pulling a few hoses and costs virtually nothing. A BCC is not mandated by installation of an electronic boost controller. A BCC is mandated by wanting to exceed stock boost levels - which can be accomplished by various means. If you put on a DP and cat back exhaust, you'll likely hit fuel cut on hard runs in the cold weather.
4. An EBC is NOT a priority. Priorities should be: Turbo timer, boost gauge, intake or drop in filter, DP, Cat Back exhaust, then boost controller - either manual or electric. Oh yea, then you'll also need new tires - especially the rears! The above mods will run under $2K and are known as BPU - Basic Performance Upgrades in Supra parlance. BPU level performance is 400rwhp. All of the above mods are easy do it yourselfers - especially with mkiv.com as a guide. You can learn A LOT from mkiv.com, although I appreciate your comment about the FAQ section being down - great info there.
5. Yes, you need a boost gauge. Suggest you get an electric one with peak hold function. 18 psi is a typical max boost level for BPU mods. Boost gauge is another easy DIY - many put in the clock position. I put it in the A pillar mount along with an EGT gauge.
6. Don't know about lowering springs - cosmetic as far as I'm concerned.
7. Air intake - careful here. Depending on how you do this, you may not see much if any performance gain if you end up sucking hot air. A K&N drop in filter in the existing air box is the cheapest and easiest way to reduce inlet pressure loss on thhe turbos and increase performance.
8. After market Blow off valves - not needed, no real performance benefit, but sound really cool.
Email me at
[email protected] if you have any further questions. I check it almost every day. I've owned a 97TT for just over a year now and have taken it from bone stock to a little past BPU in that time. Have learned a lot - mostly from MKIV.com and supraforums, but still have a lot to learn.
Jim
97TT BPU
12.6 @ 113