Front or Top Mount

A front mount won't give you any more horsepower on track with better cooling it may give you more stable power
If anything due to increased weight the cheap eBay ones with huge pipe runs may give you a little less bhp per ton

for a road car with up to around 380hp a top mount such as the ARC or recore with latest high performance cores & thermal barrier over rocker cover is all you want really. Tuners slammed the top mount as wanted fleece your money & then the chinks made the monkey metal kits & everyone went ebay crazy & fooked up their inner wings & bumpers.
If people took a bit of time to test temps you will see the top mount is quite capable with a little bit of thought.
I've used ARC for good 10years at 330 to 350hp & still use standard pistons without issue to date. Expect the newer cores on top mounts will be better due to design & no age related issues of the now old ARC ones so it a better current option.
If running serious high power, doing a lot of track work with high power car or live in a hot country then a big front mount can be only way to keep temps low.
Pick what suites your use as just bolting it on the average 1bar GTiR won't really be an upgrade in all honesty.

I have both a top mount and a auto bahn fmic and tbh there is not much wieght difference between the two.... so the wieght difference must be the extra pipework .... when you offset that against the brackets and tmic shroud i doubt there is any difference in bhp to tonne...

I've 2 pace mounts and a se nissan front mount they are lighter than the autobahn but not by a great deal but they are considerably heavier than my top mount