I've just bought a 2002 TT 225 with the intention of turning it into a track car. First mods on the car will be a FMIC and 3" exhaust, it's already got a CDA air filter (are these any good?). I've seen ToyoSport do both a FMIC and 3" exhaust at reasonable price. Anyone had experience of these? Are they decent quality? Any comments good or bad appreciated.

Lots of people have used the Toyosport 600x300 intercooler with good effect. AKA the wellycooler . It seems these days you can only get it with 76mm hose connections. This too me is to big for nearly all applications you only really need 2.5 inch. I run a boost products 600x300 on my track TT. Runs over 500bhp and works really well, only has 2.5 inch connectors which makes life easier mounting it as it's pretty close to stock size piping.

https://www.ebay.co.uk/itm/intercooler- ... 3571070728?

I ran a toyosports 3 inch down pipe for a while and it worked well, Fitted quite well too. The downpipe is a PITA to fit though , you have to drop the front subframe to get it fitted.

Thanks for the response. My aim is to double the output, so I'm aiming for at least 450!! Would love 500+ as a mate has a mk4 1.8T (4-mo) running 520 ish.

Regarding aero, are TT's stable on track or do I need a bigger wing? (Does a V6 extension make any difference?)

I'd like to track it and build it in stages (I previously built a mk2 Golf) Obviously will be doing suspension and brakes but I heard TTs can be unstable. Will also probably go for a Power insert for the haldex to make that more predictable.

TT is not inherently unstable on track. Bigger wings and splitters generate downforce so the car will corner better. The standard Haldex can be a bit hit and miss on track and can be inconsistent so in that way I think the powertrack inserts help this. Stripping weight and brake upgrades are the first thing to do. Weight reduction helps everything, braking, acceleration cornering etc, And the TT is lardy.