Roadsport Questions

[jimmyVX]

I have been looking at a few Sigma Powered Roadsport's and have a couple of questions that hopefully someone can help me with:

1. I drove a 150bhp version on throttle bodies yesterday - Was this an aftermarket upgrade or would it have left the factory like this?

2. The last car I drove struck me as being a little slow through the revs - does a lightweight flywheel make a significant improvement on this?

3. Do the cars with throttle bodies struggle with track day noise limits anymore than a car without?

Thanks in advance.

[RedCat7]

I have had a Roadsport Sigma 150 SV which I built from a kit in 2015. I use it on the Road and Track.

1) A 150 hp Sigma with Caterham branded TBs was an option. Also has hotter cams, stiffer valve springs and an Modine oil cooler.

2) A lightened flywheel was standard on a Sigma 140 that replaced the 150 in 2011. The 140 doesn't have TBs or an oil cooler but does have the lightened flywheel and a more reliable (all ally) radiator. I'd imagine most Sigma 125/150s have been upgraded to the all alloy rad since the plastic capped radiators were notorious for springing a leak (I went through 2 before upgrading). I don't feel a need for a LF but if the engine ever has to come out I'll no doubt succumb to bout of upgraditis!

3) I've not heard of the TBs being a problem for trackday noise but mine has failed a 92dBA drive-by limit at Brands due to exhaust noise. A repack with Acoustafil did the trick - lowering the static reading from 100 to 97 dBA.