First off, what he describes is not "engine mods" - they are bolt-ons and maintenance issues.
The filter is probably one of a million CAI's (cold air intake) on the market.
Just google CAI or you can look in the galleries on this forum for all the pics you need. CAI add's a minimal amount of HP but has more to do with sound of the motor (IMO)
Coilovers - no harm in fitting if they are the right ones for the car (obviously)
At the end of the day, it will depend on you, the overall condition of both cars, and what you are willing to spend to get the 6 the way you want it.
The filter is probably one of a million CAI's (cold air intake) on the market.
Just google CAI or you can look in the galleries on this forum for all the pics you need. CAI add's a minimal amount of HP but has more to do with sound of the motor (IMO)
Coilovers - no harm in fitting if they are the right ones for the car (obviously)
At the end of the day, it will depend on you, the overall condition of both cars, and what you are willing to spend to get the 6 the way you want it.