So I had replaced my stock Zorst on my XJ6 ( Aka FZ6R Fazer )
The stock Zorst had a cat , the replacement is straight through SS with baffler ( removable but left in )
Its a 2009 model , Injection . I have also changed the drivetrain ( larger front sprocket / smaller rear )

Now I notice the bike feels slightly 'suffocated' seems as though its slightly struggling for air . Also the top end is not as fast as it was with the older pipe .

The general consensus online suggests a remap , if you agree , is it hard to do yourself? I am a Techie by trade , so I think I could do it with the right module and software . I wondered with the price of the remapping modules , if I should just pay someone else to do it . I wondered what the price would be ?

A remap will probably cost a couple hundred quid and run up on a dyno to fine tune things. I put my 1400 on a dyno a few months ago and although not needed, I will be having mine remapped over the winter because when I bought the bike, after market exhaust was making popping and backfires after hard acceleration on the over run.

I have the same , lots of bangs and splutters , fun at first but getting a little irritating. Initial throttle seems to be too sudden/ hard ( almost sounds like it is flooding ) , seems like the throttle curve needs to be adjusted to allow a more progressive curve , for a less jerky feel .
Does anyone have any experience with DIY kits ? I get a bit of an ego kick out of doing things myself .

If you have the zzr1400 you will find it difficult as the "brain" is in an anti-tamper cage, but if you have the necessary software and the confidence then go for it.                                                                                                                                                                             

There's only one way to do it properly, on a dyno.

When you reflash the ECU you can put a custom ignition curve on it, that will sort out the lean running down low that's required to pass the emissions testing.

Then tweak the AFR's and Bob's your dad's brother.

I had similar on my rocket. I fitted straight through collector (no cat) and immediately lost some torque mid range. Apparently, to do with harmonics/backpressure. Changing the baffle may smooth out the gaps at lower revs. Its a toss up between useable power across the range and Peak Horsepower. So do we like grunt or license loosing top end :)

Dyno would be good for full tune up but u may need a power commander for the dyno to plug into.

I was lucky in that there is a free tool for triumph to add new tunes. Maybe there is dedicated XJ6 site that can offer guidance.

I'd say to anyone changing pipes or intake to get a power commander, dead easy to use, has for gearing up on the front and rear sprockets I would think your now way over geared, do you really need any more top speed and it will only kill acceleration I tried it on a Fireblade but found standard gearing best