you have 5k to spend you can build a fast all motor si with that. just about every body is turbo charging there car now a days. you want cheap power i say nitrous. you . if you want power all the time i say turbo or super charger. if you want relable power i say tuned all motor that you can take pride in spanking some turbo cars ass with. but thats just my opinion its your car do whatever you want