There's really no need to get all up in arms over this. It's a car, and like pretty much any car that's stock from the factory, it's a base starting point for performance increases which is typically what modding is all about.
A Lotus has never been about power or straight line acceleration, but this one is reasonably close to be worth (in my opinion) spending a few coins to improve it, which is what I'm doing. I also enjoy doing this.
There's also two types of weight reduction; static weight and rotating weight. The Honda report was only talking about static weight reduction. Reducing rotating weight, especially unsprung rotating weight is by far much more beneficial. The 2 areas where that's doable are wheels and brake rotors. Engine flywheel and/or clutch (if it's a manual trans.) is another area where the benefit is greater than the amount of weight removed. Better oils that reduce friction and lower resistance can also help.
On the scale of benefit to cost, the cheapest way to start reducing weight is to replace the 43 lb factory battery with a 13 lb Antigravity 40ah battery (GRP sells these) which currently is $819. That's an instant 30 lb reduction with no modifications necessary; slides right into the factory mounts.
The prices start to go up from there for mod improvements.
The next best value (from my experience) was the Eventuri, which cost $1,600 but delivered a clean increase of 16 hp and 15 ft lbs of torque to the rear wheels. I know GRP's same-day test of the Eventuri and other intakes didn't produce those kinds of numbers, but I suspect it was because the ECU didn't have enough time to adjust to each of them. I've done multiple dyno runs stretched out over months, and the results are always consistent.
Next I would put lighter wheels as a good mod.
@Aerie has some nice offerings that will typically remove a combined weight of about 24 lbs for all 4 wheels. That's unsprung rotating weight (URW). There are several different opinions of how much of a weight reduction benefit that gives, from anywhere to the equivalent of 4x to 10x the amount of static weight. Just to be conservative, even if you go with the lowest of 4x, removing 24 lbs of URW would have the equivalent effect of removing 96 lbs of static weight. That you can feel. A set of forged aluminum wheels from Aerie will be around $3k (providing tariffs don't change that) which includes shipping. They're well-made, with good finishes.
I know a lot of people do 3rd cat deletes, but I didn't do that so I don't have any data to share. According to Jubu, that supposedly frees up about 5 hp to the rear wheels so that may be worthwhile, and it's relatively cheap if you don't mind the extra noise. Many want the noise, but I didn't.
The titanium exhaust is nice, but at $2,500 it's a bit pricey and isn't going to give you the same benefit spending that same amount of money would on a lighter set of wheels. Depends on your budget and what you want to spend. The benefit of the titanium exhaust is a reduction in weight of about 18 lbs (for the Aerie), and when I dynoed it, there was an increase in torque up to about 2800 rpm, which was nice. I feel more torque at the lower rpms is what the Emira needs the most.
Now you start getting into the really expensive mods. Seats are going to be above $6k, but you do get about a 66 lb reduction in weight. According to
@kitkat it does get much louder inside the car; the factory seats apparently absorb a lot of noise. This mod is debatable for a street build, but probably worthwhile for a track focused build.
Next would be either expensive wheels even lighter than what Aerie provides, but now you're up around $10k. What I've chosen to do is go with
@Warren-RB RacingBrake's carbon ceramic rotor kit. Also not cheap at $11,600, but it's a reduction of about 23 lbs of URW which according to the 4x formula, will have the effect of removing 92 lbs of static weight. In addition, there should be a drastic reduction in brake dust issues. So between the lighter Aerie wheels and the RB CCB rotors, that's an equivalent weight reduction of 188 lbs, not to mention the actual static weight reduction.
So do you 'have' to do any of this? No, of course not. The Emira as-is is a really nice sports car. If you want a bit more performance, I would say based on my experience, the Eventuri will do the most for you, even before the lighter battery. After that, it's up to you, your budget, and how much you want to do and spend.
