Ever thought how loud the road noise is coming from the back of your S14? There is a very good reason for this: when Nissan were thinking of ways to save money on this car, they discovered two massive gaps they could avoid soundproofing. By dealing with these, the amount of road noise is quite dramatically reduced.
Try breathing-out through your nose whilst half pinching your nostrils. This is akin to what your engine has to do to get exhaust gases past a catalytic converter! This obviously has an impact on the car's performance. It is a simple matter to replace the cat with a de-cat pipe.
Every car, by nature, has a degree of body flex whilst driving. This flexing causes the handling to be jittery on uneven surfaces and in intense driving situations. It is possible to reduce this significantly by fitting a strut brace in the engine bay. It is possible to get rear strut braces, but this guide deals with the more common front brace.
A lot of people like to make their S14 a bit more anonymous by de-badging it. This is fine, however, when the Nissan badge is removed from the bonnet, you are left with two locator pin holes to fill somehow. This is why I preferred the replace the badge with an alternative.