Eibach Springs Review
Lowering your car is a tricky proposition. It's certainly tempting to cut or heat-treat your stock springs, which will give you the lower appearance you're looking for at the expense of unpredictable handling. The experts recommend getting a $1000 coil-over setup, which are the 'best' way to lower a car, except that they cost an arm and a leg.
Is there a middle ground?
Yes. Swap out your factory springs for performance lowering springs. You can use these with your stock shocks & struts and cost around ~$200. New springs lower your car safely (although maybe not as much as a coil-over setup can do safely) and give you the look you're after, as well as improving handling and cornering ability.
When I decided to lower my car, I had to do a bit of research. I didn't know a thing about the subject; in fact, I didn't even know much about cars in particular. Anyone who knows about Sentras is aware of their unfortunate lack of wheel travel, unlike Civics and Integras:
The trick was to find springs that would lower the car within the allowable range of the factory suspension. After a bit of searching and discussion on the B15 Sentra Message Board, I was pointed toward Eibach Springs, manufacturer of OEM springs and performance suspension products.
The Sentra in its stock form cannot take being lowered more than 1.5 inches without sacrificing wheel travel and killing the suspension, not to mention jeopardizing control of the vehicle. Eibach designs its spring sets spceifically for each vehicle and makes two sets of springs for the Sentra: the Pro-Kit (front: 1.0in, rear: 1.2 in) and the Sportlines (front: 1.5in, rear: 1.4in). From my discussion with other Sentra tuners nationwide via the message board, I found that most of the SE owners with their tighter suspension setup went with the Sportline springs, while GXE/XE owners with their softer suspension tuning opted for the Pro-Kit (*NOTE: Keith Sipmann's Project B15 Sentra XE uses Sportline springs).
Check out this section of the Eibach FAQ from their homepage:
I ordered my Pro-Kit from Stillen for $215 shipped, and I had a mechanic friend install them for free (well, a really nice cheesecake from The Cheesecake Factory). Installation can run from $40 per spring at speed shops to $70 per spring at dealerships (IF they would even install them for you, since they're not factory parts). Installation can take up to 3~4 hours for an experienced mechanic, since you have to take the suspension apart for all four wheels. You'll need an alignment after installing your new springs.
As soon as you put them on, you can notice the difference visually. I didn't think one inch would be much of a drop, but I could tell right away when Denise came out of the garage. She definitely brought a smile to my face when I first saw her. After I got in the driver's seat, she felt a little lower to sit in, as well (you get used to it). I immediately felt a stiffer ride, and while many people want to have as smooth a ride as possible, I felt the road better, and Denise was more sensitive to bumps and holes in the road. The major difference was that she felt SQUAT and very balanced. She really hugged the road, and when cornering, she controlled much better. No more leaning to one side when taking a turn a little fast, and nose-dive during hard braking was eliminated. It was actually WEIRD how much better she handled after swapping in the Eibachs, because who would've thought a 1-inch drop would make that big a difference? Well, it most certainly did.
The drop is not extreme enough that you really fear speed bumps and high-angle driveways. I was almost disappointed that I didn't have to crawl over speed bumps rice-boy-style. Sometimes I'll even go over one at regular speed because I didn't see it, and I have absolutely no scraping. The only downside is that potholes feel much rougher now (even small ones can rattle your teeth), and differences in road height (on the highway, especially) are very rough too. Sometimes it feels like the car bottoms out on those 'joints' on the highway. On normal driving, however, it's easy to forget you're driving in a lowered car at all.
Here are a few pictures illustrating the difference between Pro-Kits versus stock springs, and Pro-Kits versus Sportlines (thanks to trance34 at B15Sentra.net):
Denise with stock springs
close-up of rear left wheel with Eibach Pro-Kit
profile, with stock springs
profile, with Eibach Pro-Kit
Here is a picture comparing Pro-Kits (left) with Sportlines (right):
Notice the difference in drop. I can barely tell the difference msyelf, but the Sportlines are actually cheaper than the Pro-Kits (Sportlines are around $175~$200, while Pro-Kits are $200~$250). I've been told that Sportlines are engineered primarily to lower a car as low as possible while still being safe to drive, while Pro-Kits lower for ideal performance, which means not lowering to a Sportline-level.
Personally, I lowered my car for looks and found improved handling as an added bonus. I opted for the Pro-Kit because I was afraid my car couldn't handle Sportlines, and while my car may not be as low as I would have liked, I take solace in the fact that it's lowered as much as it should be. The notice in Denise is clear even with the Pro-Kit, and I don't have the rice-boy image of slamming my car to the ground (although I think Sportlines are nice).
I'm extremely happy with my Pro-Kit. Visually, it finished off the exterior mods I'd made to Denise and gave her a more 'complete,' sporty look. Performance-wise, I gained aggressive handling and slightly better throttle response when stomping the throttle (a nice added touch to the visual improvement =P).
If your car has sporty suspension and/or stiff shocks & struts, I'd go with the Sportlines for their more aggressive appearance. For cars with softer suspension, or if your goal is optimizing your handling, go with the Pro-Kit (they're the best of both worlds).
Check out the results of Tire Rack's Road Test of Eibach performance suspension products.