Old one but hey its EVE. Things move slowly in here. Here are my thoughts.
A tristan is pretty much always countered or disengaged because its slow and/or lacks DPS.
Your brawler is a scram kiter. A painfully slow scramkiter. Every brawler out there will be able to brawl you.
Ppl have told you to remove the nos which is a good idea. Never use nos or neut on a scram kiting frigate unless it has a range bonus. Remove the CPU rig but do NOT tank it further. You need a speed rig. If I were you I would remove one more hull rig and fly with 2 mobility rigs. A slow scram kiter is a dead scram kiter.
Kiting Tristans suffer from the stupid drones syndrome. You will only ever be able to kill AB frigs, short ranged dessies (yes you are so slow that you will want to keep an eye on the MWD dessies to) or a cruiser here and there. If you are planning on warping in on plexes I recommend SAAR and 2 mobility rigs. All those shield modules + the fact that you are slow means that even slow locking dessies with be able to catch you on warpin.
Only time I ever use a Tristan is when I want to kill drone dessies and/or hold tackle on cruisers. In which case it looks like this:
[Tristan, New Setup 9]
Damage Control II
Small Ancillary Armor Repairer, Nanite Repair Paste
Small Armor Repairer II
5MN Quad LiF Restrained Microwarpdrive
Warp Disruptor II
Small Capacitor Booster II, Navy Cap Booster 400
250mm Light ‘Scout’ Artillery I, Republic Fleet Titanium Sabot S
250mm Light ‘Scout’ Artillery I, Republic Fleet Titanium Sabot S
[empty high slot]
Small Transverse Bulkhead II
Small Auxiliary Thrusters II
Small Polycarbon Engine Housing II
Hobgoblin II x5
Hobgoblin II x3
Nanite Repair Paste x16
Republic Fleet Phased Plasma S x200
Republic Fleet Titanium Sabot S x200
Navy Cap Booster 400 x10
The point of this one is holding tackle for extended periods of time in which you take intervals of spikedamage like from drone dessies or cruisers. So if you ask me, the Tristan is not ideal for fighting frigs but it excels when messing around above its weightclass.