My suggestion is if you're going to get something else don't worry about it... but then if you insist I can tell you what you can do.. cheap stuff first exhaust and headers - you can have just the exhaust if you want but the headers really compliment it... probably about $510 all up.. go for 2" if you still want some torque or 2.25" for performance. I wouldn't worry about a hi-flo cat for the paseo cos it's not that restrictive anyway. pod filter/cold air - k&n filter(or your brand choice) usually pick up for about $80.. easy to put in, 2 ways you can go about cold air... you can do it the less efficient way and just build some heat shielding around the filter or you can set up the filter to get air from the front and under the car. Feel free to ask me about that as it's a bit lengthy Engine internals - you can upgrade your pistons, rods, etc. Raise the compression ratio on your engine but don't go too hardcore with that. then there's everything else like your ignition, chip, etc etc I got the cold air, headers and 2.25" exhaust.. feel like I wasted my money now cos I'm going to throw a 3s-gte in.. 2L turbo celica engine :D